[PATCH] D33555: [scudo] Check the return values of the pthread_* functions

[Kostya Kortchinsky via Phabricator via llvm-commits]

cryptoad created this revision.

Currently we are not enforcing the success of `pthread_once`, and
`pthread_setspecific`. Errors could lead to harder to debug issues later in
the thread's life. This adds checks for a 0 return value for both.
If `pthread_setspecific` fails in the teardown path, opt for an immediate
teardown as opposed to a fatal failure.


https://reviews.llvm.org/D33555

Files:
  lib/scudo/scudo_tls_linux.cpp


Index: lib/scudo/scudo_tls_linux.cpp
===================================================================
--- lib/scudo/scudo_tls_linux.cpp
+++ lib/scudo/scudo_tls_linux.cpp
@@ -32,15 +32,17 @@
 THREADLOCAL ScudoThreadContext ThreadLocalContext;
 
 static void teardownThread(void *Ptr) {
-  uptr Iteration = reinterpret_cast<uptr>(Ptr);
+  uptr I = reinterpret_cast<uptr>(Ptr);
   // The glibc POSIX thread-local-storage deallocation routine calls user
   // provided destructors in a loop of PTHREAD_DESTRUCTOR_ITERATIONS.
   // We want to be called last since other destructors might call free and the
   // like, so we wait until PTHREAD_DESTRUCTOR_ITERATIONS before draining the
   // quarantine and swallowing the cache.
-  if (Iteration < PTHREAD_DESTRUCTOR_ITERATIONS) {
-    pthread_setspecific(PThreadKey, reinterpret_cast<void *>(Iteration + 1));
-    return;
+  if (I < PTHREAD_DESTRUCTOR_ITERATIONS) {
+    // If pthread_setspecific fails, we will go ahead with the teardown.
+    if (LIKELY(pthread_setspecific(PThreadKey,
+                                   reinterpret_cast<void *>(I + 1)) == 0))
+      return;
   }
   ThreadLocalContext.commitBack();
   ScudoThreadState = ThreadTornDown;
@@ -53,8 +55,8 @@
 }
 
 void initThread() {
-  pthread_once(&GlobalInitialized, initOnce);
-  pthread_setspecific(PThreadKey, reinterpret_cast<void *>(1));
+  CHECK_EQ(pthread_once(&GlobalInitialized, initOnce), 0);
+  CHECK_EQ(pthread_setspecific(PThreadKey, reinterpret_cast<void *>(1)), 0);
   ThreadLocalContext.init();
   ScudoThreadState = ThreadInitialized;
 }


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