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component(err-ctx): trap on a misaligned pointer - #14626
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`error-context.debug-message` bounds-checked the guest-provided destination pointer for the string's `(ptr, len)` pair, but not its alignment, and then wrote the pair via `<str as Lower>::linear_lower_to_memory`, which `debug_assert!`s that the offset is 4-byte aligned. A guest passing an in-bounds but misaligned pointer could therefore panic the host in debug builds, while release builds performed the unaligned write. Check the pointer's alignment before lowering and trap with "invalid debug message pointer: not aligned", the same way the stream/future read and write paths in this file report misaligned pointers. Assisted-by: claude:claude-opus-5-5 Signed-off-by: Roman Volosatovs <rvolosatovs@riseup.net>
alexcrichton
approved these changes
Oct 9, 2026
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error-context.debug-messagebounds-checked the guest-provided destination pointer for the string's(ptr, len)pair, but not its alignment, and then wrote the pair via<str as Lower>::linear_lower_to_memory, whichdebug_assert!s that the offset is 4-byte aligned. A guest passing an in-bounds but misaligned pointer could therefore panic the host in debug builds, while release builds performed the unaligned write.Check the pointer's alignment before lowering and trap with "invalid debug message pointer: not aligned", the same way the stream/future read and write paths in this file report misaligned pointers.