[compiler-rt] r208333 - [ASan] Fix coverage behavior when a PC belongs to an unknown address range.

[Alexey Samsonov]

This test fails for me locally. Please check if r208356 fixes it properly.


On Thu, May 8, 2014 at 9:09 AM, Sergey Matveev <earthdok at google.com> wrote:

> Author: smatveev
> Date: Thu May  8 11:09:54 2014
> New Revision: 208333
>
> URL: http://llvm.org/viewvc/llvm-project?rev=208333&view=rev
> Log:
> [ASan] Fix coverage behavior when a PC belongs to an unknown address range.
>
> This happens, e.g., when coverage data is collected for a module which is
> then
> dlclose()'d. Currently this causes CovDump() to ignore all PCs that are
> greater
> than the unrecognized PC. In other words, unloading a module causes ASan to
> silently ignore any coverage data for modules loaded at higher addresses.
> Instead we should just skip the unrecognized PCs.
>
> Added:
>     compiler-rt/trunk/test/asan/TestCases/Linux/coverage-module-unloaded.cc
> Modified:
>     compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage.cc
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage.cc?rev=208333&r1=208332&r2=208333&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage.cc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage.cc Thu May
>  8 11:09:54 2014
> @@ -90,8 +90,9 @@ void CovDump() {
>         i++) {
>      if ((prot & MemoryMappingLayout::kProtectionExecute) == 0)
>        continue;
> +    while (vb < ve && *vb < mb) vb++;
>      if (vb >= ve) break;
> -    if (mb <= *vb && *vb < me) {
> +    if (*vb < me) {
>        offsets.clear();
>        const uptr *old_vb = vb;
>        CHECK_LE(off, *vb);
>
> Added:
> compiler-rt/trunk/test/asan/TestCases/Linux/coverage-module-unloaded.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/coverage-module-unloaded.cc?rev=208333&view=auto
>
> ==============================================================================
> ---
> compiler-rt/trunk/test/asan/TestCases/Linux/coverage-module-unloaded.cc
> (added)
> +++
> compiler-rt/trunk/test/asan/TestCases/Linux/coverage-module-unloaded.cc Thu
> May  8 11:09:54 2014
> @@ -0,0 +1,55 @@
> +// Check that unloading a module doesn't break coverage dumping for
> remaining
> +// modules.
> +// RUN: %clangxx_asan -mllvm -asan-coverage=1 -DSHARED %s -shared -o
> %T/libcoverage_module_unloaded_test_1.so -fPIC
> +// RUN: %clangxx_asan -mllvm -asan-coverage=1 -DSHARED %s -shared -o
> %T/libcoverage_module_unloaded_test_2.so -fPIC
> +// RUN: %clangxx_asan -mllvm -asan-coverage=1 -DSO_DIR=\"%T\" %s -o %t
> -Wl,-R,\$ORIGIN -L%T -lcoverage_test
> +// RUN: export ASAN_OPTIONS=coverage=1:verbosity=1
> +// RUN: %t 2>&1         | FileCheck %s
> +// RUN: %t foo 2>&1         | FileCheck %s
> +//
> +// https://code.google.com/p/address-sanitizer/issues/detail?id=263
> +// XFAIL: android
> +
> +#include <assert.h>
> +#include <dlfcn.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +
> +#ifdef SHARED
> +extern "C" {
> +void bar() { printf("bar\n"); }
> +}
> +#else
> +
> +int main(int argc, char **argv) {
> +  fprintf(stderr, "PID: %d\n", getpid());
> +  fprintf(stderr, "Opening %s\n", SO_DIR
> "/libcoverage_module_disappeared_test_1.so");
> +  void *handle1 =
> +      dlopen(SO_DIR "/libcoverage_module_disappeared_test_1.so",
> RTLD_LAZY);
> +  assert(handle1);
> +  void (*bar1)() = (void (*)())dlsym(handle1, "bar");
> +  assert(bar1);
> +  bar1();
> +  void *handle2 =
> +      dlopen(SO_DIR "/libcoverage_module_disappeared_test_2.so",
> RTLD_LAZY);
> +  assert(handle2);
> +  void (*bar2)() = (void (*)())dlsym(handle2, "bar");
> +  assert(bar2);
> +  bar2();
> +
> +  // It matters whether the unloaded module has a higher or lower address
> range
> +  // than the remaining one. Make sure to test both cases.
> +  if (argc < 2)
> +    dlclose(bar1 < bar2 ? handle1 : handle2);
> +  else
> +    dlclose(bar1 < bar2 ? handle2 : handle1);
> +  return 0;
> +}
> +#endif
> +
> +// CHECK: PID: [[PID:[0-9]+]]
> +// CHECK: [[PID]].sancov: 1 PCs written
> +// CHECK: .so.[[PID]]
> +// If we get coverage for both DSOs, it means the module wasn't unloaded
> and
> +// this test is useless.
> +// CHECK-not: .so.[[PID]]
>
>
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-- 
Alexey Samsonov, Mountain View, CA
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