Copilot commented on code in PR #13661:
URL: https://github.com/apache/trafficserver/pull/13661#discussion_r3983985498
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src/tsutil/Regex.cc:
##########
@@ -79,6 +80,46 @@ my_free(void *ptr, void * /*caller*/)
free(ptr);
}
+//----------------------------------------------------------------------------
+// One match context is shared by every thread that matches through it, and
PCRE2
+// requires a distinct JIT stack per thread, so the stack comes from a callback
+// invoked at match time rather than a pointer baked in when the context is
built.
+//
+// The per thread stack is held in a pthread key rather than a thread_local. A
+// thread_local with a destructor registers it through __cxa_thread_atexit,
which
+// takes the dynamic loader lock; doing that from a match would invert lock
order
+// against a dlopen caller running a plugin's static initialization. See the
same
+// hazard described at Diags::tag_activated. A pthread key registers its
destructor
+// once, at key creation, and never from the matching path.
+pthread_key_t jit_stack_key;
+pthread_once_t jit_stack_key_once = PTHREAD_ONCE_INIT;
+
+void
+destroy_jit_stack(void *stack)
+{
+ if (stack != nullptr) {
+ pcre2_jit_stack_free(static_cast<pcre2_jit_stack *>(stack));
+ }
+}
+
+void
+make_jit_stack_key()
+{
+ pthread_key_create(&jit_stack_key, destroy_jit_stack);
Review Comment:
`pthread_key_create` can fail (for example with `EAGAIN` or `ENOMEM`), but
this return value is ignored. `pthread_once` will still mark the initializer
complete while `jit_stack_key` remains invalid/default-initialized, so the
following `pthread_getspecific`/`pthread_setspecific` calls can use an invalid
or unrelated key and return an unrelated pointer as a JIT stack. Check the
creation result and make the callback handle key-initialization failure before
using the key.
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