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Fix tests, warnings and a memory leak #3

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@vries vries commented Sep 25, 2018

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jeffmahoney pushed a commit that referenced this pull request Apr 14, 2019
Running gdbserver under Valgrind I get:

  ==26925== Conditional jump or move depends on uninitialised value(s)
  ==26925==    at 0x473E7F: i387_cache_to_xsave(regcache*, void*) (i387-fp.c:579)
  ==26925==    by 0x46E3ED: x86_fill_xstateregset(regcache*, void*) (linux-x86-low.c:418)
  ==26925==    by 0x45E747: regsets_store_inferior_registers(regsets_info*, regcache*) (linux-low.c:5456)
  ==26925==    by 0x45EEF8: linux_store_registers(regcache*, int) (linux-low.c:5731)
  ==26925==    by 0x426441: regcache_invalidate_thread(thread_info*) (regcache.c:89)
  ==26925==    by 0x45CCAF: linux_resume_one_lwp_throw(lwp_info*, int, int, siginfo_t*) (linux-low.c:4447)
  ==26925==    by 0x45CE2A: linux_resume_one_lwp(lwp_info*, int, int, siginfo_t*) (linux-low.c:4519)
  ==26925==    by 0x45E17C: proceed_one_lwp(thread_info*, lwp_info*) (linux-low.c:5216)
  ==26925==    by 0x45DC81: linux_resume_one_thread(thread_info*, bool) (linux-low.c:5031)
  ==26925==    by 0x45DD34: linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}::operator()(thread_info*) const (linux-low.c:5095)
  ==26925==    by 0x462907: void for_each_thread<linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}>(linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}) (gdbthread.h:150)
  ==26925==    by 0x45DE62: linux_resume(thread_resume*, unsigned long) (linux-low.c:5093)
  ==26925==
  ==26925== Conditional jump or move depends on uninitialised value(s)
  ==26925==    at 0x473EBD: i387_cache_to_xsave(regcache*, void*) (i387-fp.c:586)
  ==26925==    by 0x46E3ED: x86_fill_xstateregset(regcache*, void*) (linux-x86-low.c:418)
  ==26925==    by 0x45E747: regsets_store_inferior_registers(regsets_info*, regcache*) (linux-low.c:5456)
  ==26925==    by 0x45EEF8: linux_store_registers(regcache*, int) (linux-low.c:5731)
  ==26925==    by 0x426441: regcache_invalidate_thread(thread_info*) (regcache.c:89)
  ==26925==    by 0x45CCAF: linux_resume_one_lwp_throw(lwp_info*, int, int, siginfo_t*) (linux-low.c:4447)
  ==26925==    by 0x45CE2A: linux_resume_one_lwp(lwp_info*, int, int, siginfo_t*) (linux-low.c:4519)
  ==26925==    by 0x45E17C: proceed_one_lwp(thread_info*, lwp_info*) (linux-low.c:5216)
  ==26925==    by 0x45DC81: linux_resume_one_thread(thread_info*, bool) (linux-low.c:5031)
  ==26925==    by 0x45DD34: linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}::operator()(thread_info*) const (linux-low.c:5095)
  ==26925==    by 0x462907: void for_each_thread<linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}>(linux_resume(thread_resume*, unsigned long)::{lambda(thread_info*)#2}) (gdbthread.h:150)
  ==26925==    by 0x45DE62: linux_resume(thread_resume*, unsigned long) (linux-low.c:5093)

The problem is a type/width mismatch in code like this, in
gdbserver/i387-fp.c:

  /* Some registers are 16-bit.  */
  collect_register_by_name (regcache, "fctrl", &val);
  fp->fctrl = val;

In the above code:

 #1 - 'val' is a 64-bit unsigned long.

 #2 - "fctrl" is 32-bit in the register cache, thus half of 'val' is
      left uninitialized by collect_register_by_name, which works with
      an untyped raw buffer output (i.e., void*).

 #3 - fp->fctrl is an unsigned short (16-bit).  For some such
      registers we're masking off the uninitialized bits with 0xffff,
      but not in all cases.

We end up in such a fragile situation because
collect_registers_by_name works with an untyped output buffer pointer,
making it easy to pass a pointer to a variable of the wrong size.

Fix this by using regcache_raw_get_unsigned instead (actually a new
regcache_raw_get_unsigned_by_name wrapper), which always returns a
zero-extended ULONGEST register value.  It ends up simplifying the
i387-tdep.c code a bit, even.

gdb/gdbserver/ChangeLog:
2018-07-11  Pedro Alves  <[email protected]>

	* i387-fp.c (i387_cache_to_fsave, cache_to_fxsave)
	(i387_cache_to_xsave): Use regcache_raw_get_unsigned_by_name
	instead of collect_register_by_name.
	* regcache.c (regcache_raw_get_unsigned_by_name): New.
	* regcache.h (regcache_raw_get_unsigned_by_name): New.
jeffmahoney pushed a commit that referenced this pull request Apr 14, 2019
… gdb/23377)

This fixes a gdb.base/multi-forks.exp regression with GDBserver.

Git commit f2ffa92 ("gdb: Eliminate the 'stop_pc' global") caused
the regression by exposing a latent bug in gdbserver.

The bug is that GDBserver's implementation of the D;PID packet
incorrectly assumes that the selected thread points to the process
being detached.  This happens via the any_persistent_commands call,
which calls current_process:

  (gdb) bt
  #0  0x000000000040a57e in internal_error(char const*, int, char const*, ...)
  (file=0x4a53c0 "src/gdb/gdbserver/inferiors.c", line=212, fmt=0x4a539e "%s:
  Assertion `%s' failed.") at src/gdb/gdbserver/../common/errors.c:54
  #1  0x0000000000420acf in current_process() () at
  src/gdb/gdbserver/inferiors.c:212
  #2  0x00000000004226a0 in any_persistent_commands() () at
  gdb/gdbserver/mem-break.c:308
  #3  0x000000000042cb43 in handle_detach(char*) (own_buf=0x6f0280 "D;62ea") at
  src/gdb/gdbserver/server.c:1210
  #4  0x0000000000433af3 in process_serial_event() () at
  src/gdb/gdbserver/server.c:4055
  #5  0x0000000000434878 in handle_serial_event(int, void*) (err=0,
  client_data=0x0)

The "eliminate stop_pc" commit exposes the problem because before that
commit, GDB's switch_to_thread always read the newly-selected thread's
PC, and that would end up forcing GDBserver's selected thread to
change accordingly as side effect.  After that commit, GDB no longer
reads the thread's PC, and GDBserver does not switch the thread.

Fix this by removing the assumption from GDBserver.

gdb/gdbserver/ChangeLog:
2018-07-11  Pedro Alves  <[email protected]>

	PR gdb/23377
	* mem-break.c (any_persistent_commands): Add process_info
	parameter and use it instead of relying on the current process.
	Change return type to bool.
	* mem-break.h (any_persistent_commands): Add process_info
	parameter and change return type to bool.
	* server.c (handle_detach): Remove require_running_or_return call.
	Look up the process_info for the process we're about to detach.
	If not found, return back error to GDB.  Adjust
	any_persistent_commands call to pass down a process pointer.
jeffmahoney pushed a commit that referenced this pull request Apr 14, 2019
…b/23379)

This commit fixes a 8.1->8.2 regression exposed by
gdb.python/py-evthreads.exp when testing with
--target_board=native-gdbserver.

gdb.log shows:

  src/gdb/thread.c:93: internal-error: thread_info* inferior_thread(): Assertion `tp' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Quit this debugging session? (y or n) FAIL: gdb.python/py-evthreads.exp: run to breakpoint 1 (GDB internal error)

A backtrace shows (frames #2 and #10 highlighted) that the assertion
fails when GDB is setting up the connection to the remote target, in
non-stop mode:

  #0  0x0000000000622ff0 in internal_error(char const*, int, char const*, ...) (file=0xc1ad98 "src/gdb/thread.c", line=93, fmt=0xc1ad20 "%s: Assertion `%s' failed.") at src/gdb/common/errors.c:54
  #1  0x000000000089567e in inferior_thread() () at src/gdb/thread.c:93
= #2  0x00000000004da91d in get_event_thread() () at src/gdb/python/py-threadevent.c:38
  #3  0x00000000004da9b7 in create_thread_event_object(_typeobject*, _object*) (py_type=0x11574c0 <continue_event_object_type>, thread=0x0)
      at src/gdb/python/py-threadevent.c:60
  #4  0x00000000004bf6fe in create_continue_event_object() () at src/gdb/python/py-continueevent.c:27
  #5  0x00000000004bf738 in emit_continue_event(ptid_t) (ptid=...) at src/gdb/python/py-continueevent.c:40
  #6  0x00000000004c7d47 in python_on_resume(ptid_t) (ptid=...) at src/gdb/python/py-inferior.c:108
  #7  0x0000000000485bfb in std::_Function_handler<void (ptid_t), void (*)(ptid_t)>::_M_invoke(std::_Any_data const&, ptid_t&&) (__functor=..., __args#0=...) at /usr/include/c++/7/bits/std_function.h:316
  #8  0x000000000089b416 in std::function<void (ptid_t)>::operator()(ptid_t) const (this=0x12aa600, __args#0=...)
      at /usr/include/c++/7/bits/std_function.h:706
  #9  0x000000000089aa0e in gdb::observers::observable<ptid_t>::notify(ptid_t) const (this=0x118a7a0 <gdb::observers::target_resumed>, args#0=...)
      at src/gdb/common/observable.h:106
= #10 0x0000000000896fbe in set_running(ptid_t, int) (ptid=..., running=1) at src/gdb/thread.c:880
  #11 0x00000000007f750f in remote_target::remote_add_thread(ptid_t, bool, bool) (this=0x12c5440, ptid=..., running=true, executing=true) at src/gdb/remote.c:2434
  #12 0x00000000007f779d in remote_target::remote_notice_new_inferior(ptid_t, int) (this=0x12c5440, currthread=..., executing=1)
      at src/gdb/remote.c:2515
  #13 0x00000000007f9c44 in remote_target::update_thread_list() (this=0x12c5440) at src/gdb/remote.c:3831
  #14 0x00000000007fb922 in remote_target::start_remote(int, int) (this=0x12c5440, from_tty=0, extended_p=0)
      at src/gdb/remote.c:4655
  #15 0x00000000007fd102 in remote_target::open_1(char const*, int, int) (name=0x1a4f45e "localhost:2346", from_tty=0, extended_p=0)
      at src/gdb/remote.c:5638
  #16 0x00000000007fbec1 in remote_target::open(char const*, int) (name=0x1a4f45e "localhost:2346", from_tty=0)
      at src/gdb/remote.c:4862

So on frame #10, we're marking a newly-discovered thread as running,
and that causes the Python API to emit a gdb.ContinueEvent.
gdb.ContinueEvent is a gdb.ThreadEvent, and as such includes the event
thread as the "inferior_thread" attribute.  The problem is that when
we get to frame #3/#4, we lost all references to the thread that is
being marked as running.  create_continue_event_object assumes that it
is the current thread, which is not true in this case.

Fix this by passing down the right thread in
create_continue_event_object.  Also remove
create_thread_event_object's default argument and have the only other
caller left pass down the right thread explicitly too.

gdb/ChangeLog:
2018-08-24  Pedro Alves  <[email protected]>
	    Simon Marchi  <[email protected]>

	PR gdb/23379
	* python/py-continueevent.c: Include "gdbthread.h".
	(create_continue_event_object): Add intro comment.  Add 'ptid'
	parameter.  Use it to find thread to pass to
	create_thread_event_object.
	(emit_continue_event): Pass PTID down to
	create_continue_event_object.
	* python/py-event.h (py_get_event_thread): Declare.
	(create_thread_event_object): Remove default from 'thread'
	parameter.
	* python/py-stopevent.c (create_stop_event_object): Use
	py_get_event_thread.
	* python/py-threadevent.c (get_event_thread): Rename to ...
	(py_get_event_thread): ... this, make extern, add 'ptid' parameter
	and use it to find the thread.
	(create_thread_event_object): Assert that THREAD isn't null.
	Don't find the event thread here.
jeffmahoney pushed a commit that referenced this pull request Apr 14, 2019
This change adds an optional output parameter BLOCK to
find_pc_partial_function.  If BLOCK is non-null, then *BLOCK will be
set to the address of the block corresponding to the function symbol
if such a symbol was found during lookup.  Otherwise it's set to the
NULL value.  Callers may wish to use the block information to
determine whether the block contains any non-contiguous ranges.  The
caller may also iterate over or examine those ranges.

When I first started looking at the broken stepping behavior associated
with functions w/ non-contiguous ranges, I found that I could "fix"
the problem by disabling the find_pc_partial_function cache.  It would
sometimes happen that the PC passed in would be between the low and
high cache values, but would be in some other function that happens to
be placed in between the ranges for the cached function.  This caused
incorrect values to be returned.

So dealing with this cache turns out to be very important for fixing
this problem.  I explored three different ways of dealing with the
cache.

My first approach was to clear the cache when a block was encountered
with more than one range.  This would cause the non-cache pathway to
be executed on the next call to find_pc_partial_function.

Another approach, which I suspect is slightly faster, checks to see
whether the PC is within one of the ranges associated with the cached
block.  If so, then the cached values can be used.  It falls back to
the original behavior if there is no cached block.

The current approach, suggested by Simon Marchi, is to restrict the
low/high pc values recorded for the cache to the beginning and end of
the range containing the PC value under consideration.  This allows us
to retain the simple (and fast) test for determining whether the
memoized (cached) values apply to the PC passed to
find_pc_partial_function.

Another choice that had to be made regards setting *ADDRESS and
*ENDADDR.  There are three possibilities which might make sense:

1) *ADDRESS and *ENDADDR represent the lowest and highest address
   of the function.
2) *ADDRESS and *ENDADDR are set to the start and end address of
   the range containing the entry pc.
3) *ADDRESS and *ENDADDR are set to the start and end address of
   the range in which PC is found.

An earlier version of this patch implemented option #1.  I found out
that it's not very useful though and, in fact, returns results that
are incorrect when used in the context of determining the start and
end of the function for doing prologue analysis.  While debugging a
function in which the entry pc was in the second range (of a function
containing two non-contiguous ranges), I noticed that
amd64_skip_prologue called find_pc_partial_function - the returned
start address was set to the beginning of the first range.  This is
incorrect for this function.  What was also interesting was that this
first invocation of find_pc_partial_function correctly set the cache
for the PC on which it had been invoked, but a slightly later call
from skip_prologue_using_sal could not use this cached value because
it was now being used to lookup the very lowest address of the
function - which is in a range not containing the entry pc.

Option #2 is attractive as it would provide a desirable result
when used in the context of prologue analysis.  However, many callers,
including some which do prologue analysis want the condition
*ADDRESS <= PC < *ENDADDR to hold.  This will not be the case when
find_pc_partial_function is called on a PC that's in a non-entry-pc
range.  A later patch to this series adds
find_function_entry_range_from_pc as a wrapper of
find_pc_partial_function.

Option #3 causes the *ADDRESS <= PC < *ENDADDR property to hold.  If
find_pc_partial_function is called with a PC that's within entry pc's
range, then it will correctly return the limits of that range.  So, if
the result of a minsym search is passed to find_pc_partial_function
to find the limits, then correct results will be achieved.  Returned
limits (for prologue analysis) won't be correct when PC is within some
other (non-entry-pc) range.  I don't yet know how big of a problem
this might be; I'm guessing that it won't be a serious problem - if a
compiler generates functions which have non-contiguous ranges, then it
also probably generates DWARF2 CFI which makes a lot of the old
prologue analysis moot.

I've implemented option #3 for this version of the patch.  I don't see
any regressions for x86-64.  Moreover, I don't expect to see
regressions for other targets either simply because
find_pc_partial_function behaves the same as it did before for the
contiguous address range case.  That said, there may be some
adjustments needed if GDB encounters a function requiring prologue
analysis which occupies non-contiguous ranges.

gdb/ChangeLog:

	* symtab.h (find_pc_partial_function): Add new parameter `block'.
	* blockframe.c (cache_pc_function_block): New static global.
	(clear_pc_function_cache): Clear cache_pc_function_block.
	(find_pc_partial_function): Move comment to symtab.h.  Add
	support for non-contiguous blocks.
jeffmahoney pushed a commit that referenced this pull request Apr 14, 2019
;; Fix '`catch syscall' doesn't work for parent after `fork' is called'
;; (Philippe Waroquiers, RH BZ 1149205).
;;=fedoratest

URL: <https://sourceware.org/ml/gdb-patches/2013-05/msg00364.html>
Message-ID: <1368136582.30058.7.camel@soleil>

  From: Philippe Waroquiers <philippe dot waroquiers at skynet dot be>
  To: gdb-patches at sourceware dot org
  Subject: RFA: fix gdb_assert caused by 'catch signal ...' and fork
  Date: Thu, 09 May 2013 23:56:22 +0200

  The attached patch fixes a gdb_assert caused by the combination of catch
  signal and fork:
    break-catch-sig.c:152: internal-error: signal_catchpoint_remove_location: Assertion `signal_catch_counts[iter] > 0' failed.

  The problem is that the signal_catch_counts is decremented by detach_breakpoints.
  The fix consists in not detaching breakpoint locations of type bp_loc_other.
  The patch introduces a new test.

Comments by Sergio Durigan Junior:

  I addded a specific testcase for this patch, which tests exactly the
  issue that the customer is facing.  This patch does not solve the
  whole problem of catching a syscall and forking (for more details,
  see <https://sourceware.org/bugzilla/show_bug.cgi?id=13457>,
  specifically comment #3), but it solves the issue reported by the
  customer.

  I also removed the original testcase of this patch, because it
  relied on "catch signal", which is a command that is not implemented
  in this version of GDB.

commit bd9673a
Author: Philippe Waroquiers <[email protected]>
Date:   Tue May 21 18:47:05 2013 +0000

    Fix internal error caused by interaction between catch signal and fork
jeffmahoney pushed a commit that referenced this pull request Apr 16, 2019
Errors that happen in nested sourced files (when a sourced file sources
another file) lead to a wrong error message, or use-after-free.

For example, if I put this in "a.gdb":

    command_that_doesnt_exist

and this in "b.gdb":

   source a.gdb

and try to "source b.gdb" in GDB, the result may look like this:

    (gdb) source b.gdb
    b.gdb:1: Error in sourced command file:
    _that_doesnt_exist:1: Error in sourced command file:
    Undefined command: "command_that_doesnt_exist".  Try "help".

Notice the wrong file name where "a.gdb" should be.  The exact result
may differ, depending on the feelings of the memory allocator.

What happens is:

- The "source a.gdb" command is saved by command_line_append_input_line
  in command_line_input's static buffer.
- Since we are sourcing a file, the script_from_file function stores the
  script name (a.gdb) in the source_file_name global.  However, it doesn't
  do a copy, it just saves a pointer to command_line_input's static buffer.
- The "command_that_doesnt_exist" command is saved by
  command_line_append_input_line in command_line_input's static buffer.
  Depending on what xrealloc does, source_file_name may now point to
  freed memory, or at the minimum the data it was pointing to was
  overwritten.
- When the error is handled in script_from_file, we dererence
  source_file_name to print the name of the file in which the error
  occured.

To fix it, I made source_file_name an std::string, so that keeps a copy of
the file name instead of pointing to a buffer with a too small
lifetime.

With this patch, the expected filename is printed, and no use-after-free
occurs:

    (gdb) source b.gdb
    b.gdb:1: Error in sourced command file:
    a.gdb:1: Error in sourced command file:
    Undefined command: "command_that_doesnt_exist".  Try "help".

I passed explicit template parameters to make_scoped_restore
(<std::string, const std::string &>), so that the second parameter is
passed by reference and avoid a copy.

It was not as obvious as I first thought to change gdb.base/source.exp
to test this, because source commands inside sourced files are
interpreted relative to GDB's current working directory, not the
directory of the currently sourced file.  As a workaround, I moved the
snippet that tests errors after the snippet that adds the source
directory to the search path.  This way, the "source source-error-1.gdb"
line in source-error.exp manages to find the file.

For reference, here is what ASAN reports when use-after-free occurs:

(gdb) source b.gdb
=================================================================
==18498==ERROR: AddressSanitizer: heap-use-after-free on address 0x60c000019847 at pc 0x7f1d3645de8e bp 0x7ffdcb892e50 sp 0x7ffdcb8925c8
READ of size 6 at 0x60c000019847 thread T0
    #0 0x7f1d3645de8d in printf_common /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors_format.inc:546
    #1 0x7f1d36477175 in __interceptor_vasprintf /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:1525
    #2 0x5632eaffa277 in xstrvprintf(char const*, __va_list_tag*) /home/simark/src/binutils-gdb/gdb/common/common-utils.c:122
    #3 0x5632eaff96d1 in throw_it /home/simark/src/binutils-gdb/gdb/common/common-exceptions.c:351
    #4 0x5632eaff98df in throw_verror(errors, char const*, __va_list_tag*) /home/simark/src/binutils-gdb/gdb/common/common-exceptions.c:379
    #5 0x5632eaff9a2a in throw_error(errors, char const*, ...) /home/simark/src/binutils-gdb/gdb/common/common-exceptions.c:394
    #6 0x5632eafca21a in script_from_file(_IO_FILE*, char const*) /home/simark/src/binutils-gdb/gdb/cli/cli-script.c:1553
    #7 0x5632eaf8a500 in source_script_from_stream /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:569
    #8 0x5632eaf8a735 in source_script_with_search /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:605
    #9 0x5632eaf8ab20 in source_command /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:664
    #10 0x5632eafa8b4a in do_const_cfunc /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:106
    #11 0x5632eafb0687 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:1892
    #12 0x5632ebf3dd87 in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:630
    #13 0x5632eb3b25d3 in command_handler(char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:583
    #14 0x5632ebf3cf09 in read_command_file(_IO_FILE*) /home/simark/src/binutils-gdb/gdb/top.c:425
    #15 0x5632eafca054 in script_from_file(_IO_FILE*, char const*) /home/simark/src/binutils-gdb/gdb/cli/cli-script.c:1547
    #16 0x5632eaf8a500 in source_script_from_stream /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:569
    #17 0x5632eaf8a735 in source_script_with_search /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:605
    #18 0x5632eaf8ab20 in source_command /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:664
    #19 0x5632eafa8b4a in do_const_cfunc /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:106
    #20 0x5632eafb0687 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:1892
    #21 0x5632ebf3dd87 in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:630
    #22 0x5632eb3b25d3 in command_handler(char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:583
    #23 0x5632eb3b2f87 in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /home/simark/src/binutils-gdb/gdb/event-top.c:770
    #24 0x5632eb3b0fe1 in gdb_rl_callback_handler /home/simark/src/binutils-gdb/gdb/event-top.c:213
    #25 0x5632ec1c8729 in rl_callback_read_char /home/simark/src/binutils-gdb/readline/callback.c:220
    #26 0x5632eb3b0b8f in gdb_rl_callback_read_char_wrapper_noexcept /home/simark/src/binutils-gdb/gdb/event-top.c:175
    #27 0x5632eb3b0da1 in gdb_rl_callback_read_char_wrapper /home/simark/src/binutils-gdb/gdb/event-top.c:192
    #28 0x5632eb3b2186 in stdin_event_handler(int, void*) /home/simark/src/binutils-gdb/gdb/event-top.c:511
    #29 0x5632eb3aa6a9 in handle_file_event /home/simark/src/binutils-gdb/gdb/event-loop.c:733
    #30 0x5632eb3aaf41 in gdb_wait_for_event /home/simark/src/binutils-gdb/gdb/event-loop.c:859
    #31 0x5632eb3a88ea in gdb_do_one_event() /home/simark/src/binutils-gdb/gdb/event-loop.c:347
    #32 0x5632eb3a89bf in start_event_loop() /home/simark/src/binutils-gdb/gdb/event-loop.c:371
    #33 0x5632eb76fbfc in captured_command_loop /home/simark/src/binutils-gdb/gdb/main.c:330
    #34 0x5632eb772ea8 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1176
    #35 0x5632eb773071 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1192
    #36 0x5632eabfe7f9 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32
    #37 0x7f1d3554f222 in __libc_start_main (/usr/lib/libc.so.6+0x24222)
    #38 0x5632eabfe5dd in _start (/home/simark/build/binutils-gdb/gdb/gdb+0x195d5dd)

0x60c000019847 is located 7 bytes inside of 128-byte region [0x60c000019840,0x60c0000198c0)
freed by thread T0 here:
    #0 0x7f1d36502491 in __interceptor_realloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:105
    #1 0x5632eaff9f47 in xrealloc /home/simark/src/binutils-gdb/gdb/common/common-utils.c:62
    #2 0x5632eaff6b44 in buffer_grow(buffer*, char const*, unsigned long) /home/simark/src/binutils-gdb/gdb/common/buffer.c:40
    #3 0x5632eb3b271d in command_line_append_input_line /home/simark/src/binutils-gdb/gdb/event-top.c:614
    #4 0x5632eb3b28c6 in handle_line_of_input(buffer*, char const*, int, char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:654
    #5 0x5632ebf402a6 in command_line_input(char const*, char const*) /home/simark/src/binutils-gdb/gdb/top.c:1252
    #6 0x5632ebf3cee9 in read_command_file(_IO_FILE*) /home/simark/src/binutils-gdb/gdb/top.c:422
    #7 0x5632eafca054 in script_from_file(_IO_FILE*, char const*) /home/simark/src/binutils-gdb/gdb/cli/cli-script.c:1547
    #8 0x5632eaf8a500 in source_script_from_stream /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:569
    #9 0x5632eaf8a735 in source_script_with_search /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:605
    #10 0x5632eaf8ab20 in source_command /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:664
    #11 0x5632eafa8b4a in do_const_cfunc /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:106
    #12 0x5632eafb0687 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:1892
    #13 0x5632ebf3dd87 in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:630
    #14 0x5632eb3b25d3 in command_handler(char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:583
    #15 0x5632ebf3cf09 in read_command_file(_IO_FILE*) /home/simark/src/binutils-gdb/gdb/top.c:425
    #16 0x5632eafca054 in script_from_file(_IO_FILE*, char const*) /home/simark/src/binutils-gdb/gdb/cli/cli-script.c:1547
    #17 0x5632eaf8a500 in source_script_from_stream /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:569
    #18 0x5632eaf8a735 in source_script_with_search /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:605
    #19 0x5632eaf8ab20 in source_command /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:664
    #20 0x5632eafa8b4a in do_const_cfunc /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:106
    #21 0x5632eafb0687 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:1892
    #22 0x5632ebf3dd87 in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:630
    #23 0x5632eb3b25d3 in command_handler(char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:583
    #24 0x5632eb3b2f87 in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /home/simark/src/binutils-gdb/gdb/event-top.c:770
    #25 0x5632eb3b0fe1 in gdb_rl_callback_handler /home/simark/src/binutils-gdb/gdb/event-top.c:213
    #26 0x5632ec1c8729 in rl_callback_read_char /home/simark/src/binutils-gdb/readline/callback.c:220
    #27 0x5632eb3b0b8f in gdb_rl_callback_read_char_wrapper_noexcept /home/simark/src/binutils-gdb/gdb/event-top.c:175
    #28 0x5632eb3b0da1 in gdb_rl_callback_read_char_wrapper /home/simark/src/binutils-gdb/gdb/event-top.c:192
    #29 0x5632eb3b2186 in stdin_event_handler(int, void*) /home/simark/src/binutils-gdb/gdb/event-top.c:511

previously allocated by thread T0 here:
    #0 0x7f1d36502491 in __interceptor_realloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:105
    #1 0x5632eaff9f47 in xrealloc /home/simark/src/binutils-gdb/gdb/common/common-utils.c:62
    #2 0x5632eaff6b44 in buffer_grow(buffer*, char const*, unsigned long) /home/simark/src/binutils-gdb/gdb/common/buffer.c:40
    #3 0x5632eb3b271d in command_line_append_input_line /home/simark/src/binutils-gdb/gdb/event-top.c:614
    #4 0x5632eb3b28c6 in handle_line_of_input(buffer*, char const*, int, char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:654
    #5 0x5632ebf402a6 in command_line_input(char const*, char const*) /home/simark/src/binutils-gdb/gdb/top.c:1252
    #6 0x5632ebf3cee9 in read_command_file(_IO_FILE*) /home/simark/src/binutils-gdb/gdb/top.c:422
    #7 0x5632eafca054 in script_from_file(_IO_FILE*, char const*) /home/simark/src/binutils-gdb/gdb/cli/cli-script.c:1547
    #8 0x5632eaf8a500 in source_script_from_stream /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:569
    #9 0x5632eaf8a735 in source_script_with_search /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:605
    #10 0x5632eaf8ab20 in source_command /home/simark/src/binutils-gdb/gdb/cli/cli-cmds.c:664
    #11 0x5632eafa8b4a in do_const_cfunc /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:106
    #12 0x5632eafb0687 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:1892
    #13 0x5632ebf3dd87 in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:630
    #14 0x5632eb3b25d3 in command_handler(char const*) /home/simark/src/binutils-gdb/gdb/event-top.c:583
    #15 0x5632eb3b2f87 in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /home/simark/src/binutils-gdb/gdb/event-top.c:770
    #16 0x5632eb3b0fe1 in gdb_rl_callback_handler /home/simark/src/binutils-gdb/gdb/event-top.c:213
    #17 0x5632ec1c8729 in rl_callback_read_char /home/simark/src/binutils-gdb/readline/callback.c:220
    #18 0x5632eb3b0b8f in gdb_rl_callback_read_char_wrapper_noexcept /home/simark/src/binutils-gdb/gdb/event-top.c:175
    #19 0x5632eb3b0da1 in gdb_rl_callback_read_char_wrapper /home/simark/src/binutils-gdb/gdb/event-top.c:192
    #20 0x5632eb3b2186 in stdin_event_handler(int, void*) /home/simark/src/binutils-gdb/gdb/event-top.c:511
    #21 0x5632eb3aa6a9 in handle_file_event /home/simark/src/binutils-gdb/gdb/event-loop.c:733
    #22 0x5632eb3aaf41 in gdb_wait_for_event /home/simark/src/binutils-gdb/gdb/event-loop.c:859
    #23 0x5632eb3a88ea in gdb_do_one_event() /home/simark/src/binutils-gdb/gdb/event-loop.c:347
    #24 0x5632eb3a89bf in start_event_loop() /home/simark/src/binutils-gdb/gdb/event-loop.c:371
    #25 0x5632eb76fbfc in captured_command_loop /home/simark/src/binutils-gdb/gdb/main.c:330
    #26 0x5632eb772ea8 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1176
    #27 0x5632eb773071 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1192
    #28 0x5632eabfe7f9 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32
    #29 0x7f1d3554f222 in __libc_start_main (/usr/lib/libc.so.6+0x24222)

SUMMARY: AddressSanitizer: heap-use-after-free /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors_format.inc:546 in printf_common

gdb/ChangeLog:

	* top.h (source_file_name): Change to std::string.
	* top.c (source_file_name): Likewise.
	(command_line_input): Adjust.
	* cli/cli-script.c (script_from_file): Adjust.

gdb/testsuite/ChangeLog:

	* gdb.base/source.exp: Move "error in sourced script" code to
	the end.
	* gdb.base/source-error.gdb: Move contents to
	source-error-1.gdb.  Add new code to source source-error-1.gdb.
	* gdb.base/source-error-1.gdb: New file, from previous
	source-error.gdb.
jeffmahoney pushed a commit that referenced this pull request Apr 16, 2019
Commit ab42892 ("Fix vertical scrolling of TUI source window")
introduced a use-after-free in source_cache::get_source_lines.

At the beginning of the method, we get the fullname of the symtab:

    const char *fullname = symtab_to_fullname (s);

fullname points to the string owned by the symtab (s.fullname).  When we
later do

    scoped_fd desc = open_source_file (s);

s.fullname gets reallocated (even though the string contents may not
change).  The fullname local variable now points to freed memory.

To avoid it, refresh the value of fullname after calling
open_source_file.

Here is the ASan report:

$ ./gdb -nx --data-directory=data-directory ./a.out
(gdb) start
Temporary breakpoint 1 at 0x1130: file test.cpp, line 12.
Starting program: /home/simark/build/binutils-gdb/gdb/a.out

Temporary breakpoint 1, main () at test.cpp:12
=================================================================
==26068==ERROR: AddressSanitizer: heap-use-after-free on address 0x6210003d4100 at pc 0x7fed89a34681 bp 0x7ffd8d185d80 sp 0x7ffd8d185528
READ of size 2 at 0x6210003d4100 thread T0
    #0 0x7fed89a34680 in __interceptor_strlen /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:301
    #1 0x55b6edf6c2f7 in std::char_traits<char>::length(char const*) /usr/include/c++/8.2.1/bits/char_traits.h:320
    #2 0x55b6edf6c9b2 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&) /usr/include/c++/8.2.1/bits/basic_string.h:516
    #3 0x55b6ef09121b in source_cache::get_source_lines(symtab*, int, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*) /home/simark/src/binutils-gdb/gdb/source-cache.c:214
    #4 0x55b6ef0a15cb in print_source_lines_base /home/simark/src/binutils-gdb/gdb/source.c:1340
    #5 0x55b6ef0a2045 in print_source_lines(symtab*, int, int, enum_flags<print_source_lines_flag>) /home/simark/src/binutils-gdb/gdb/source.c:1415
    #6 0x55b6ef112c87 in print_frame_info(frame_info*, int, print_what, int, int) /home/simark/src/binutils-gdb/gdb/stack.c:914
    #7 0x55b6ef10e90d in print_stack_frame(frame_info*, int, print_what, int) /home/simark/src/binutils-gdb/gdb/stack.c:180
    #8 0x55b6ee9592f8 in print_stop_location /home/simark/src/binutils-gdb/gdb/infrun.c:7853
    #9 0x55b6ee95948f in print_stop_event(ui_out*) /home/simark/src/binutils-gdb/gdb/infrun.c:7870
    #10 0x55b6ef34b962 in tui_on_normal_stop /home/simark/src/binutils-gdb/gdb/tui/tui-interp.c:98
    #11 0x55b6ee01a14d in std::_Function_handler<void (bpstats*, int), void (*)(bpstats*, int)>::_M_invoke(std::_Any_data const&, bpstats*&&, int&&) /usr/include/c++/8.2.1/bits/std_function.h:297
    #12 0x55b6ee965415 in std::function<void (bpstats*, int)>::operator()(bpstats*, int) const /usr/include/c++/8.2.1/bits/std_function.h:687
    #13 0x55b6ee962f1b in gdb::observers::observable<bpstats*, int>::notify(bpstats*, int) const /home/simark/src/binutils-gdb/gdb/common/observable.h:106
    #14 0x55b6ee95a6e7 in normal_stop() /home/simark/src/binutils-gdb/gdb/infrun.c:8142
    #15 0x55b6ee93f236 in fetch_inferior_event(void*) /home/simark/src/binutils-gdb/gdb/infrun.c:3782
    #16 0x55b6ee8f2641 in inferior_event_handler(inferior_event_type, void*) /home/simark/src/binutils-gdb/gdb/inf-loop.c:43
    #17 0x55b6eea2a1f0 in handle_target_event /home/simark/src/binutils-gdb/gdb/linux-nat.c:4358
    #18 0x55b6ee7045f1 in handle_file_event /home/simark/src/binutils-gdb/gdb/event-loop.c:733
    #19 0x55b6ee704e89 in gdb_wait_for_event /home/simark/src/binutils-gdb/gdb/event-loop.c:859
    #20 0x55b6ee7027b5 in gdb_do_one_event() /home/simark/src/binutils-gdb/gdb/event-loop.c:322
    #21 0x55b6ee702907 in start_event_loop() /home/simark/src/binutils-gdb/gdb/event-loop.c:371
    #22 0x55b6eeadfc16 in captured_command_loop /home/simark/src/binutils-gdb/gdb/main.c:331
    #23 0x55b6eeae2ef9 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1174
    #24 0x55b6eeae30c2 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1190
    #25 0x55b6edf4fa89 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32
    #26 0x7fed88ad8222 in __libc_start_main (/usr/lib/libc.so.6+0x24222)
    #27 0x55b6edf4f86d in _start (/home/simark/build/binutils-gdb/gdb/gdb+0x197186d)

0x6210003d4100 is located 0 bytes inside of 4096-byte region [0x6210003d4100,0x6210003d5100)
freed by thread T0 here:
    #0 0x7fed89a8ac19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:66
    #1 0x55b6edfe12df in xfree<char> /home/simark/src/binutils-gdb/gdb/common/common-utils.h:60
    #2 0x55b6edfea675 in gdb::xfree_deleter<char>::operator()(char*) const /home/simark/src/binutils-gdb/gdb/common/gdb_unique_ptr.h:34
    #3 0x55b6edfe532c in std::unique_ptr<char, gdb::xfree_deleter<char> >::reset(char*) /usr/include/c++/8.2.1/bits/unique_ptr.h:382
    #4 0x55b6edfe7329 in std::unique_ptr<char, gdb::xfree_deleter<char> >::operator=(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /usr/include/c++/8.2.1/bits/unique_ptr.h:289
    #5 0x55b6ef09ec2b in find_and_open_source(char const*, char const*, std::unique_ptr<char, gdb::xfree_deleter<char> >*) /home/simark/src/binutils-gdb/gdb/source.c:990
    #6 0x55b6ef09f56a in open_source_file(symtab*) /home/simark/src/binutils-gdb/gdb/source.c:1069
    #7 0x55b6ef090f78 in source_cache::get_source_lines(symtab*, int, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*) /home/simark/src/binutils-gdb/gdb/source-cache.c:205
    #8 0x55b6ef0a15cb in print_source_lines_base /home/simark/src/binutils-gdb/gdb/source.c:1340
    #9 0x55b6ef0a2045 in print_source_lines(symtab*, int, int, enum_flags<print_source_lines_flag>) /home/simark/src/binutils-gdb/gdb/source.c:1415
    #10 0x55b6ef112c87 in print_frame_info(frame_info*, int, print_what, int, int) /home/simark/src/binutils-gdb/gdb/stack.c:914
    #11 0x55b6ef10e90d in print_stack_frame(frame_info*, int, print_what, int) /home/simark/src/binutils-gdb/gdb/stack.c:180
    #12 0x55b6ee9592f8 in print_stop_location /home/simark/src/binutils-gdb/gdb/infrun.c:7853
    #13 0x55b6ee95948f in print_stop_event(ui_out*) /home/simark/src/binutils-gdb/gdb/infrun.c:7870
    #14 0x55b6ef34b962 in tui_on_normal_stop /home/simark/src/binutils-gdb/gdb/tui/tui-interp.c:98
    #15 0x55b6ee01a14d in std::_Function_handler<void (bpstats*, int), void (*)(bpstats*, int)>::_M_invoke(std::_Any_data const&, bpstats*&&, int&&) /usr/include/c++/8.2.1/bits/std_function.h:297
    #16 0x55b6ee965415 in std::function<void (bpstats*, int)>::operator()(bpstats*, int) const /usr/include/c++/8.2.1/bits/std_function.h:687
    #17 0x55b6ee962f1b in gdb::observers::observable<bpstats*, int>::notify(bpstats*, int) const /home/simark/src/binutils-gdb/gdb/common/observable.h:106
    #18 0x55b6ee95a6e7 in normal_stop() /home/simark/src/binutils-gdb/gdb/infrun.c:8142
    #19 0x55b6ee93f236 in fetch_inferior_event(void*) /home/simark/src/binutils-gdb/gdb/infrun.c:3782
    #20 0x55b6ee8f2641 in inferior_event_handler(inferior_event_type, void*) /home/simark/src/binutils-gdb/gdb/inf-loop.c:43
    #21 0x55b6eea2a1f0 in handle_target_event /home/simark/src/binutils-gdb/gdb/linux-nat.c:4358
    #22 0x55b6ee7045f1 in handle_file_event /home/simark/src/binutils-gdb/gdb/event-loop.c:733
    #23 0x55b6ee704e89 in gdb_wait_for_event /home/simark/src/binutils-gdb/gdb/event-loop.c:859
    #24 0x55b6ee7027b5 in gdb_do_one_event() /home/simark/src/binutils-gdb/gdb/event-loop.c:322
    #25 0x55b6ee702907 in start_event_loop() /home/simark/src/binutils-gdb/gdb/event-loop.c:371
    #26 0x55b6eeadfc16 in captured_command_loop /home/simark/src/binutils-gdb/gdb/main.c:331
    #27 0x55b6eeae2ef9 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1174
    #28 0x55b6eeae30c2 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1190
    #29 0x55b6edf4fa89 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32

previously allocated by thread T0 here:
    #0 0x7fed89a8b019 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
    #1 0x7fed88af983f in realpath@@GLIBC_2.3 (/usr/lib/libc.so.6+0x4583f)
    #2 0x7fed899dbbbc in __interceptor_canonicalize_file_name /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:3297
    #3 0x55b6ee376a03 in gdb_realpath(char const*) /home/simark/src/binutils-gdb/gdb/common/pathstuff.c:72
    #4 0x55b6ef09ec12 in find_and_open_source(char const*, char const*, std::unique_ptr<char, gdb::xfree_deleter<char> >*) /home/simark/src/binutils-gdb/gdb/source.c:990
    #5 0x55b6ef09f56a in open_source_file(symtab*) /home/simark/src/binutils-gdb/gdb/source.c:1069
    #6 0x55b6ef0a0f12 in print_source_lines_base /home/simark/src/binutils-gdb/gdb/source.c:1270
    #7 0x55b6ef0a2045 in print_source_lines(symtab*, int, int, enum_flags<print_source_lines_flag>) /home/simark/src/binutils-gdb/gdb/source.c:1415
    #8 0x55b6ef112c87 in print_frame_info(frame_info*, int, print_what, int, int) /home/simark/src/binutils-gdb/gdb/stack.c:914
    #9 0x55b6ef10e90d in print_stack_frame(frame_info*, int, print_what, int) /home/simark/src/binutils-gdb/gdb/stack.c:180
    #10 0x55b6ee9592f8 in print_stop_location /home/simark/src/binutils-gdb/gdb/infrun.c:7853
    #11 0x55b6ee95948f in print_stop_event(ui_out*) /home/simark/src/binutils-gdb/gdb/infrun.c:7870
    #12 0x55b6ef34b962 in tui_on_normal_stop /home/simark/src/binutils-gdb/gdb/tui/tui-interp.c:98
    #13 0x55b6ee01a14d in std::_Function_handler<void (bpstats*, int), void (*)(bpstats*, int)>::_M_invoke(std::_Any_data const&, bpstats*&&, int&&) /usr/include/c++/8.2.1/bits/std_function.h:297
    #14 0x55b6ee965415 in std::function<void (bpstats*, int)>::operator()(bpstats*, int) const /usr/include/c++/8.2.1/bits/std_function.h:687
    #15 0x55b6ee962f1b in gdb::observers::observable<bpstats*, int>::notify(bpstats*, int) const /home/simark/src/binutils-gdb/gdb/common/observable.h:106
    #16 0x55b6ee95a6e7 in normal_stop() /home/simark/src/binutils-gdb/gdb/infrun.c:8142
    #17 0x55b6ee93f236 in fetch_inferior_event(void*) /home/simark/src/binutils-gdb/gdb/infrun.c:3782
    #18 0x55b6ee8f2641 in inferior_event_handler(inferior_event_type, void*) /home/simark/src/binutils-gdb/gdb/inf-loop.c:43
    #19 0x55b6eea2a1f0 in handle_target_event /home/simark/src/binutils-gdb/gdb/linux-nat.c:4358
    #20 0x55b6ee7045f1 in handle_file_event /home/simark/src/binutils-gdb/gdb/event-loop.c:733
    #21 0x55b6ee704e89 in gdb_wait_for_event /home/simark/src/binutils-gdb/gdb/event-loop.c:859
    #22 0x55b6ee7027b5 in gdb_do_one_event() /home/simark/src/binutils-gdb/gdb/event-loop.c:322
    #23 0x55b6ee702907 in start_event_loop() /home/simark/src/binutils-gdb/gdb/event-loop.c:371
    #24 0x55b6eeadfc16 in captured_command_loop /home/simark/src/binutils-gdb/gdb/main.c:331
    #25 0x55b6eeae2ef9 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1174
    #26 0x55b6eeae30c2 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1190
    #27 0x55b6edf4fa89 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32
    #28 0x7fed88ad8222 in __libc_start_main (/usr/lib/libc.so.6+0x24222)

gdb/ChangeLog:

	* source-cache.c (source_cache::get_source_lines): Re-read
	fullname after calling open_source_file.
jeffmahoney pushed a commit that referenced this pull request Apr 16, 2019
…trace

The test  gdb.threads/watchthreads-reorder.exp verifies that the
'set debug infrun 1' debug output does not crash GDB.

Under high load, the test can still cause a GDB internal error (see details
below).

This patch fixes this crash, and improves/factorises some wait kind traces.

Tested on debian/amd64 + run one test with 'set debug infrun 1'.

Changes compared to the first version:
  * Handles the suggestions of Kevin to trace the relevant elements
    of the wait status (this is done by calling target_waitstatus_to_string).
  * Some other changes to factorise wait status tracing.

Note that using target_waitstatus_to_string instead of the 'locally printed'
status kind strings means that debug trace that was using strings such as:
   "EXITED" or "TARGET_WAITKIND_EXITED"
will now use what is printed by target_waitstatus_to_string e.g.
   "exited".

gdb/ChangeLog
2019-04-01  Philippe Waroquiers  <[email protected]>

	* infrun.c (stop_all_threads): If debug_infrun, always
	trace the wait status after wait_one, using
	target_waitstatus_to_string and target_pid_to_str.
	(handle_inferior_event): Replace various trace of
	wait status kind by a single trace.
	* gdb/gnu-nat.c (gnu_nat_target::wait): Replace local
	wait status kind image by target_waitstatus_to_string.
	* target/waitstatus.c (target_waitstatus_to_string): Fix
	obsolete comment.

  (top-gdb) bt
  #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
  #1  0x00007f3d54a0642a in __GI_abort () at abort.c:89
  #2  0x0000555c24c60e66 in dump_core () at ../../fixleaks/gdb/utils.c:201
  #3  0x0000555c24c63d49 in internal_vproblem(internal_problem *, const char *, int, const char *, typedef __va_list_tag __va_list_tag *) (problem=problem@entry=0x555c25338d40 <internal_error_problem>, file=<optimized out>, line=287,
      fmt=<optimized out>, ap=<optimized out>) at ../../fixleaks/gdb/utils.c:411
  #4  0x0000555c24c63eab in internal_verror (file=<optimized out>, line=<optimized out>, fmt=<optimized out>,
      ap=<optimized out>) at ../../fixleaks/gdb/utils.c:436
  #5  0x0000555c249e8c22 in internal_error (file=file@entry=0x555c24e0f2ad "../../fixleaks/gdb/inferior.c",
      line=line@entry=287, fmt=<optimized out>) at ../../fixleaks/gdb/common/errors.c:55
  #6  0x0000555c247d3f5c in find_inferior_pid (pid=<optimized out>) at ../../fixleaks/gdb/inferior.c:287
  #7  0x0000555c24ad2248 in find_inferior_pid (pid=<optimized out>) at ../../fixleaks/gdb/inferior.c:302
  #8  find_inferior_ptid (ptid=...) at ../../fixleaks/gdb/inferior.c:301
  #9  0x0000555c24c35f25 in find_thread_ptid (ptid=...) at ../../fixleaks/gdb/thread.c:522
  #10 0x0000555c24b0ab4d in thread_db_target::pid_to_str[abi:cxx11](ptid_t) (
      this=0x555c2532e3e0 <the_thread_db_target>, ptid=...) at ../../fixleaks/gdb/linux-thread-db.c:1637
  #11 0x0000555c24c2f420 in target_pid_to_str[abi:cxx11](ptid_t) (ptid=...) at ../../fixleaks/gdb/target.c:2083
  #12 0x0000555c24ad9cab in stop_all_threads () at ../../fixleaks/gdb/infrun.c:4373
  #13 0x0000555c24ada00f in stop_waiting (ecs=<optimized out>) at ../../fixleaks/gdb/infrun.c:7464
  #14 0x0000555c24adc401 in process_event_stop_test (ecs=ecs@entry=0x7ffc9402d9d0) at ../../fixleaks/gdb/infrun.c:6181
  ...
  (top-gdb) fr 12
  #12 0x0000555c24ad9cab in stop_all_threads () at ../../fixleaks/gdb/infrun.c:4373
  (top-gdb) p event_ptid
  $5 = {m_pid = 25419, m_lwp = 25427, m_tid = 0}
  (top-gdb) p ptid
  $6 = {m_pid = 0, m_lwp = 0, m_tid = 0}
  (top-gdb) p ws
  $7 = {kind = TARGET_WAITKIND_THREAD_EXITED, value = {integer = 0, sig = GDB_SIGNAL_0, related_pid = {m_pid = 0,
        m_lwp = 0, m_tid = 0}, execd_pathname = 0x0, syscall_number = 0}}
  (top-gdb)

The gdb.log corresponding to the above crash is:
  (gdb) PASS: gdb.threads/watchthreads-reorder.exp: reorder1: set debug infrun 1
  continue
  Continuing.
  infrun: clear_proceed_status_thread (Thread 0x7ffff7fcfb40 (LWP 25419))
  infrun: clear_proceed_status_thread (Thread 0x7ffff7310700 (LWP 25427))
  infrun: clear_proceed_status_thread (Thread 0x7ffff6b0f700 (LWP 25428))
  infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
  infrun: proceed: resuming Thread 0x7ffff7fcfb40 (LWP 25419)
  infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 0x7ffff7fcfb40 (LWP 25419)] at 0x7ffff7344317
  infrun: infrun_async(1)
  infrun: prepare_to_wait
  infrun: proceed: resuming Thread 0x7ffff7310700 (LWP 25427)
  infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 0x7ffff7310700 (LWP 25427)] at 0x5555555553d7
  infrun: prepare_to_wait
  infrun: proceed: resuming Thread 0x7ffff6b0f700 (LWP 25428)
  infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 0x7ffff6b0f700 (LWP 25428)] at 0x5555555554c8
  infrun: prepare_to_wait
  infrun: target_wait (-1.0.0, status) =
  infrun:   -1.0.0 [process -1],
  infrun:   status->kind = ignore
  infrun: TARGET_WAITKIND_IGNORE
  infrun: prepare_to_wait
  Joining the threads.
  [Thread 0x7ffff6b0f700 (LWP 25428) exited]
  infrun: target_wait (-1.0.0, status) =
  infrun:   -1.0.0 [process -1],
  infrun:   status->kind = ignore
  infrun: TARGET_WAITKIND_IGNORE
  infrun: prepare_to_wait
  infrun: target_wait (-1.0.0, status) =
  infrun:   25419.25419.0 [Thread 0x7ffff7fcfb40 (LWP 25419)],
  infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
  infrun: TARGET_WAITKIND_STOPPED
  infrun: stop_pc = 0x555555555e50
  infrun: context switch
  infrun: Switching context from Thread 0x7ffff6b0f700 (LWP 25428) to Thread 0x7ffff7fcfb40 (LWP 25419)
  infrun: BPSTAT_WHAT_STOP_NOISY
  infrun: stop_waiting
  infrun: stop_all_threads
  infrun: stop_all_threads, pass=0, iterations=0
  infrun:   Thread 0x7ffff7fcfb40 (LWP 25419) not executing
  infrun:   Thread 0x7ffff7310700 (LWP 25427) executing, need stop
  [Thread 0x7ffff7310700 (LWP 25427) exited]
  infrun: target_wait (-1.0.0, status) =
  infrun:   25419.25427.0 [LWP 25427],
  infrun:   status->kind = thread exited, status = 0
  infrun: infrun_async(0)
  ../../fixleaks/gdb/inferior.c:287: internal-error: inferior* find_inferior_pid(int): Assertion `pid != 0' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Quit this debugging session? (y or n) FAIL: gdb.threads/watchthreads-reorder.exp: reorder1: continue to breakpoint: break-at-exit (GDB internal error)
  Resyncing due to internal error.
  n
  infrun: infrun_async(1)

  This is a bug, please report it.  For instructions, see:
  <http://www.gnu.org/software/gdb/bugs/>.

  infrun: infrun_async(0)
  ../../fixleaks/gdb/inferior.c:287: internal-error: inferior* find_inferior_pid(int): Assertion `pid != 0' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Create a core file of GDB? (y or n) y
jeffmahoney pushed a commit that referenced this pull request Apr 18, 2019
;; Fix '`catch syscall' doesn't work for parent after `fork' is called'
;; (Philippe Waroquiers, RH BZ 1149205).
;;=fedoratest

URL: <https://sourceware.org/ml/gdb-patches/2013-05/msg00364.html>
Message-ID: <1368136582.30058.7.camel@soleil>

  From: Philippe Waroquiers <philippe dot waroquiers at skynet dot be>
  To: gdb-patches at sourceware dot org
  Subject: RFA: fix gdb_assert caused by 'catch signal ...' and fork
  Date: Thu, 09 May 2013 23:56:22 +0200

  The attached patch fixes a gdb_assert caused by the combination of catch
  signal and fork:
    break-catch-sig.c:152: internal-error: signal_catchpoint_remove_location: Assertion `signal_catch_counts[iter] > 0' failed.

  The problem is that the signal_catch_counts is decremented by detach_breakpoints.
  The fix consists in not detaching breakpoint locations of type bp_loc_other.
  The patch introduces a new test.

Comments by Sergio Durigan Junior:

  I addded a specific testcase for this patch, which tests exactly the
  issue that the customer is facing.  This patch does not solve the
  whole problem of catching a syscall and forking (for more details,
  see <https://sourceware.org/bugzilla/show_bug.cgi?id=13457>,
  specifically comment #3), but it solves the issue reported by the
  customer.

  I also removed the original testcase of this patch, because it
  relied on "catch signal", which is a command that is not implemented
  in this version of GDB.

commit bd9673a
Author: Philippe Waroquiers <[email protected]>
Date:   Tue May 21 18:47:05 2013 +0000

    Fix internal error caused by interaction between catch signal and fork
jeffmahoney pushed a commit that referenced this pull request Apr 23, 2019
;; Fix '`catch syscall' doesn't work for parent after `fork' is called'
;; (Philippe Waroquiers, RH BZ 1149205).
;;=fedoratest

URL: <https://sourceware.org/ml/gdb-patches/2013-05/msg00364.html>
Message-ID: <1368136582.30058.7.camel@soleil>

  From: Philippe Waroquiers <philippe dot waroquiers at skynet dot be>
  To: gdb-patches at sourceware dot org
  Subject: RFA: fix gdb_assert caused by 'catch signal ...' and fork
  Date: Thu, 09 May 2013 23:56:22 +0200

  The attached patch fixes a gdb_assert caused by the combination of catch
  signal and fork:
    break-catch-sig.c:152: internal-error: signal_catchpoint_remove_location: Assertion `signal_catch_counts[iter] > 0' failed.

  The problem is that the signal_catch_counts is decremented by detach_breakpoints.
  The fix consists in not detaching breakpoint locations of type bp_loc_other.
  The patch introduces a new test.

Comments by Sergio Durigan Junior:

  I addded a specific testcase for this patch, which tests exactly the
  issue that the customer is facing.  This patch does not solve the
  whole problem of catching a syscall and forking (for more details,
  see <https://sourceware.org/bugzilla/show_bug.cgi?id=13457>,
  specifically comment #3), but it solves the issue reported by the
  customer.

  I also removed the original testcase of this patch, because it
  relied on "catch signal", which is a command that is not implemented
  in this version of GDB.

commit bd9673a
Author: Philippe Waroquiers <[email protected]>
Date:   Tue May 21 18:47:05 2013 +0000

    Fix internal error caused by interaction between catch signal and fork
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