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

[Sergey Matveev]

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]]