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[asan] fix false dynamic-stack-buffer-overflow report with constantly-sized dynamic allocas, compiler-rt part 

See the bug report at https://github.com/google/sanitizers/issues/691. When a dynamic alloca has a constant size, ASan instrumentation will treat it as a regular dynamic alloca (insert calls to poison and unpoison), but the backend will turn it into a regular stack variable. The poisoning/unpoisoning is then broken. This patch will treat such allocas as static.

Differential Revision: http://reviews.llvm.org/D21509

llvm-svn: 273889
This commit is contained in:
Kuba Brecka 2016-06-27 15:57:53 +00:00
parent 7d03ce480a
commit 7d1ebed0c5
1 changed files with 44 additions and 0 deletions
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44
compiler-rt/test/asan/TestCases/alloca_constant_size.cc Normal file
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// Regression test for https://github.com/google/sanitizers/issues/691
// RUN: %clangxx_asan -O0 %s -o %t -fstack-protector
// RUN: %run %t 1 2>&1 | FileCheck %s
// RUN: %run %t 2 2>&1 | FileCheck %s
#include <alloca.h>
#include <stdio.h>
#include <string.h>
void f1_alloca() {
char *dynamic_buffer = (char *)alloca(200);
fprintf(stderr, "dynamic_buffer = %p\n", dynamic_buffer);
memset(dynamic_buffer, 'y', 200);
return;
}
static const int kDynamicArraySize = 200;
void f1_vla() {
char dynamic_buffer[kDynamicArraySize];
fprintf(stderr, "dynamic_buffer = %p\n", dynamic_buffer);
memset(dynamic_buffer, 'y', kDynamicArraySize);
return;
}
void f2() {
char buf[1024];
memset(buf, 'x', 1024);
}
int main(int argc, const char *argv[]) {
if (!strcmp(argv[1], "1")) {
f1_alloca();
} else if (!strcmp(argv[1], "2")) {
f1_vla();
}
f2();
fprintf(stderr, "Done.\n");
return 0;
}
// CHECK-NOT: ERROR: AddressSanitizer
// CHECK: Done.