[llvm-commits] [compiler-rt] r169335 - /compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc

[Alexander Potapenko]

Author: glider
Date: Tue Dec  4 17:30:00 2012
New Revision: 169335

URL: http://llvm.org/viewvc/llvm-project?rev=169335&view=rev
Log:
Fix a use-after-unmap bug in /proc/self/maps caching. The cached buffer was occasionally deleted in the MemoryMappingLayout destructor.

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc?rev=169335&r1=169334&r2=169335&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc Tue Dec  4 17:30:00 2012
@@ -236,7 +236,11 @@
 }
 
 MemoryMappingLayout::~MemoryMappingLayout() {
-  UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
+  // Only unmap the buffer if it is different from the cached one. Otherwise
+  // it will be unmapped when the cache is refreshed.
+  if (proc_self_maps_.data != cached_proc_self_maps_.data) {
+    UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
+  }
 }
 
 void MemoryMappingLayout::Reset() {