[compiler-rt] r258337 - [asan] print an additional hint when reporting a container overflow

[Kostya Serebryany via llvm-commits]

Author: kcc
Date: Wed Jan 20 13:49:12 2016
New Revision: 258337

URL: http://llvm.org/viewvc/llvm-project?rev=258337&view=rev
Log:
[asan] print an additional hint when reporting a container overflow

Modified:
    compiler-rt/trunk/lib/asan/asan_report.cc
    compiler-rt/trunk/test/asan/TestCases/contiguous_container_crash.cc

Modified: compiler-rt/trunk/lib/asan/asan_report.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_report.cc?rev=258337&r1=258336&r2=258337&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_report.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_report.cc Wed Jan 20 13:49:12 2016
@@ -1016,6 +1016,14 @@ static bool SuppressErrorReport(uptr pc)
   Die();
 }
 
+static void PrintContainerOverflowHint() {
+  Printf("HINT: if you don't care about these errors you may set "
+         "ASAN_OPTIONS=detect_container_overflow=0.\n"
+         "If you suspect a false positive see also: "
+         "https://github.com/google/sanitizers/wiki/"
+         "AddressSanitizerContainerOverflow.\n");
+}
+
 void ReportGenericError(uptr pc, uptr bp, uptr sp, uptr addr, bool is_write,
                         uptr access_size, u32 exp, bool fatal) {
   if (!fatal && SuppressErrorReport(pc)) return;
@@ -1032,6 +1040,7 @@ void ReportGenericError(uptr pc, uptr bp
 
   // Determine the error type.
   const char *bug_descr = "unknown-crash";
+  u8 shadow_val = 0;
   if (AddrIsInMem(addr)) {
     u8 *shadow_addr = (u8*)MemToShadow(addr);
     // If we are accessing 16 bytes, look at the second shadow byte.
@@ -1040,7 +1049,8 @@ void ReportGenericError(uptr pc, uptr bp
     // If we are in the partial right redzone, look at the next shadow byte.
     if (*shadow_addr > 0 && *shadow_addr < 128)
       shadow_addr++;
-    switch (*shadow_addr) {
+    shadow_val = *shadow_addr;
+    switch (shadow_val) {
       case kAsanHeapLeftRedzoneMagic:
       case kAsanHeapRightRedzoneMagic:
       case kAsanArrayCookieMagic:
@@ -1109,6 +1119,8 @@ void ReportGenericError(uptr pc, uptr bp
   stack.Print();
 
   DescribeAddress(addr, access_size, bug_descr);
+  if (shadow_val == kAsanContiguousContainerOOBMagic)
+    PrintContainerOverflowHint();
   ReportErrorSummary(bug_descr, &stack);
   PrintShadowMemoryForAddress(addr);
 }

Modified: compiler-rt/trunk/test/asan/TestCases/contiguous_container_crash.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/contiguous_container_crash.cc?rev=258337&r1=258336&r2=258337&view=diff
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/contiguous_container_crash.cc (original)
+++ compiler-rt/trunk/test/asan/TestCases/contiguous_container_crash.cc Wed Jan 20 13:49:12 2016
@@ -23,6 +23,7 @@ int TestCrash() {
   __sanitizer_annotate_contiguous_container(&t[0], &t[0] + 100, &t[0] + 100,
                                             &t[0] + 50);
 // CHECK-CRASH: AddressSanitizer: container-overflow
+// CHECK-CRASH: if you don't care about these errors you may set ASAN_OPTIONS=detect_container_overflow=0
   return (int)t[60 * one];  // Touches the poisoned memory.
 }