Copilot commented on code in PR #13876:
URL: https://github.com/apache/trafficserver/pull/13876#discussion_r4334751740
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src/iocore/cache/CacheWrite.cc:
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@@ -794,8 +794,8 @@ CacheVC::openWriteStartBegin(int /* event ATS_UNUSED */,
Event * /* e ATS_UNUSED
if (((err = stripe->open_write_lock(this, false, 1)) > 0)) {
ts::Metrics::Counter::increment(cache_rsb.status[op_type].failure);
ts::Metrics::Counter::increment(stripe->cache_vol->vol_rsb.status[op_type].failure);
- free_CacheVC(this);
_action.continuation->handleEvent(CACHE_EVENT_OPEN_WRITE_FAILED,
reinterpret_cast<void *>(-err));
+ free_CacheVC(this);
return EVENT_DONE;
Review Comment:
Calling the continuation before freeing `this` fixes the UAF, but it can
introduce a double-free risk if the continuation (which commonly holds the
`Action*`/VC pointer from the original `open_write` call) closes/frees the
`CacheVC` during `handleEvent`. After `handleEvent` returns,
`free_CacheVC(this)` may then free an already-freed VC. Consider using a
pattern that avoids touching or freeing `this` after invoking the callback
(e.g., transfer ownership so the callback path is responsible for cleanup, or
make `free_CacheVC` conditional/idempotent for this failure path, or defer
cleanup via scheduling so the callback can't synchronously destroy the same
object twice).
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