[webkit-changes] [WebKit/WebKit] 34d00d: Provide more crash-info in when checking for runs ...

[Marcus Plutowski]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 34d00da35e69a4c7f352e7070ab877e7a409ff70
      https://github.com/WebKit/WebKit/commit/34d00da35e69a4c7f352e7070ab877e7a409ff70
  Author: Marcus Plutowski <marcus_plutowski at apple.com>
  Date:   2024-10-02 (Wed, 02 Oct 2024)

  Changed paths:
    M Source/JavaScriptCore/jit/ExecutableAllocator.h

  Log Message:
  -----------
  Provide more crash-info in when checking for runs of zero-bytes
https://bugs.webkit.org/show_bug.cgi?id=280547
rdar://136858657

Reviewed by Keith Miller.

Previously, the crash told us that zero-bytes were present in the
destination buffer, but not whether they were present in the source
buffer. This patch fixes that without performance overhead by checking
the source buffer only if a run is detected in the destination buffer.
Moreover, while the crash stack afforded by this diagnostic is more
useful than the 'raw' crash would be, it does lose us the ability to see
the actually-corrupted instruction stream: instead of just asserting,
this patch jumps into the JIT buffer to induce a crash.

* Source/JavaScriptCore/jit/ExecutableAllocator.h:
(JSC::dieByJumpingIntoJITBufferWithInfo):
(JSC::performJITMemcpy):

Canonical link: https://commits.webkit.org/284559@main



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