Add stack overflow detection for coroutines

[jserv]

This implements canary-based stack overflow detection for hart coroutine to catch stack corruption before it leads to undefined behavior.

The implementation provides immediate detection of stack corruption with minimal performance cost.

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Summary by cubic

Adds canary-based stack overflow detection for hart coroutines. The canary is checked before and after resuming a coroutine to catch corruption early.

• New Features
  • Place the canary at the bottom of each coroutine stack buffer and initialize it in coro_create_hart.
  • Adjust usable stack bounds to skip the canary when creating the context.
  • On mismatch, print a fatal message and abort. Minimal overhead.

^{Written for commit 5093626. Summary will update automatically on new commits.}

[cubic-dev-ai]

1 issue found across 1 file

Prompt for AI agents (all 1 issues)

Understand the root cause of the following 1 issues and fix them.


<file name="coro.c">

<violation number="1" location="coro.c:251">
`coro_check_stack` only compares the `coro_t` struct field, so an actual stack overflow past the coroutine stack memory will never flip this value and the detection cannot trigger. Store the canary in the stack buffer itself and verify that sentinel instead.</violation>
</file>

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