[PATCH] D45509: [asan] Reduce flakiness in stack-overflow detection

[Kuba (Brecka) Mracek via Phabricator via llvm-commits]

kubamracek created this revision.
kubamracek added reviewers: eugenis, filcab, vitalybuka, kcc, george.karpenkov, delcypher.
kubamracek added a project: Sanitizers.
Herald added a subscriber: Sanitizers.

`IsStackOverflow` only treats accesses within 512 bytes of SP as stack-overflow. This should really be the size of a page instead.

The `scariness_score_test.cc` triggers stack overflow with frames that are even larger than a page, which can also trigger a fault that will not be recognized as stack-overflow. Let's just use smaller frames.


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D45509

Files:
  lib/sanitizer_common/sanitizer_posix_libcdep.cc
  test/asan/TestCases/scariness_score_test.cc


Index: test/asan/TestCases/scariness_score_test.cc
===================================================================
--- test/asan/TestCases/scariness_score_test.cc
+++ test/asan/TestCases/scariness_score_test.cc
@@ -115,7 +115,7 @@
 }
 
 void StackOverflow(int Idx) {
-  int some_stack[10000];
+  int some_stack[256];
   static volatile int *x;
   x = &some_stack[0];
   if (Idx > 0)
Index: lib/sanitizer_common/sanitizer_posix_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -230,7 +230,7 @@
   // take it into account.
   bool IsStackAccess = addr >= (sp & ~0xFFF) && addr < sp + 0xFFFF;
 #else
-  bool IsStackAccess = addr + 512 > sp && addr < sp + 0xFFFF;
+  bool IsStackAccess = addr + GetPageSizeCached() > sp && addr < sp + 0xFFFF;
 #endif
 
 #if __powerpc__


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