[compiler-rt] r250837 - Disabling speculative loads under asan.
Ivan Krasin via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 20 10:34:48 PDT 2015
Author: krasin
Date: Tue Oct 20 12:34:47 2015
New Revision: 250837
URL: http://llvm.org/viewvc/llvm-project?rev=250837&view=rev
Log:
Disabling speculative loads under asan.
Summary:
While instrumenting std::string with asan I discovered that speculative load might load data from poisoned region. Disabling all speculative loads for asan-annotated functions.
The test follows the std::string implementation.
Corresponding CL in llvm: http://reviews.llvm.org/D13264
Patch by Mike Aizatsky, the review page for the CL is http://reviews.llvm.org/D13265
Reviewers: aizatsky
Subscribers: kcc, llvm-commits
Differential Revision: http://reviews.llvm.org/D13905
Added:
compiler-rt/trunk/test/asan/TestCases/speculative_load.cc
Added: compiler-rt/trunk/test/asan/TestCases/speculative_load.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/speculative_load.cc?rev=250837&view=auto
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/speculative_load.cc (added)
+++ compiler-rt/trunk/test/asan/TestCases/speculative_load.cc Tue Oct 20 12:34:47 2015
@@ -0,0 +1,50 @@
+// Verifies that speculative loads from unions do not happen under asan.
+// RUN: %clangxx_asan -O0 %s -o %t && %run %t 2>&1
+// RUN: %clangxx_asan -O1 %s -o %t && %run %t 2>&1
+// RUN: %clangxx_asan -O2 %s -o %t && %run %t 2>&1
+// RUN: %clangxx_asan -O3 %s -o %t && %run %t 2>&1
+
+#include <sanitizer/asan_interface.h>
+
+struct S {
+ struct _long {
+ void* _pad;
+ const char* _ptr;
+ };
+
+ struct _short {
+ unsigned char _size;
+ char _ch[23];
+ };
+
+ union {
+ _short _s;
+ _long _l;
+ } _data;
+
+ S() {
+ _data._s._size = 0;
+ __asan_poison_memory_region(_data._s._ch, 23);
+ }
+
+ bool is_long() const {
+ return _data._s._size & 1;
+ }
+
+ const char* get_pointer() const {
+ return is_long() ? _data._l._ptr : _data._s._ch;
+ }
+};
+
+
+inline void side_effect(const void *arg) {
+ __asm__ __volatile__("" : : "r" (arg) : "memory");
+}
+
+int main(int argc, char **argv) {
+ S s;
+ side_effect(&s); // optimizer is too smart otherwise
+ const char *ptr = s.get_pointer();
+ side_effect(ptr); // force use ptr
+ return 0;
+}
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