Make prctl test check maps.
It turns out that sometimes this kernel bug can be present but not
trigger a crash. Modify the test to check for overlapping maps instead.
Bug: 32640542
Test: Verified that this fails on a device without the kernel patch
Test: (both bionic-unit-tests32 and CtsBionicTestCases32). Verified
Test: this passes on an angler.
(cherry picked from commit f1649d92f7869331ea1c4db7f2bb189489af03e6)
Change-Id: Ia3fae3ee3d01f33d8414c1796fc3e942d5b56ec8
diff --git a/tests/sys_prctl_test.cpp b/tests/sys_prctl_test.cpp
index 5a563c1..cf263b3 100644
--- a/tests/sys_prctl_test.cpp
+++ b/tests/sys_prctl_test.cpp
@@ -14,11 +14,19 @@
* limitations under the License.
*/
-#include <gtest/gtest.h>
-
+#include <inttypes.h>
+#include <stdio.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "android-base/file.h"
+#include "android-base/strings.h"
#include "private/bionic_prctl.h"
// http://b/20017123.
@@ -29,9 +37,27 @@
ASSERT_NE(MAP_FAILED, p);
ASSERT_EQ(0, mprotect(p, page_size, PROT_NONE));
ASSERT_NE(-1, prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p, page_size * 3, "anonymous map space"));
- volatile char* vp = reinterpret_cast<volatile char*>(p);
- // Below memory access causes SEGV if the memory map is screwed up.
- *(vp + page_size) = 0;
+ // Now read the maps and verify that there are no overlapped maps.
+ std::string file_data;
+ ASSERT_TRUE(android::base::ReadFileToString("/proc/self/maps", &file_data));
+
+ uintptr_t last_start = 0;
+ uintptr_t last_end = 0;
+ std::vector<std::string> lines = android::base::Split(file_data, "\n");
+ for (size_t i = 0; i < lines.size(); i++) {
+ if (lines[i].empty()) {
+ continue;
+ }
+ uintptr_t start;
+ uintptr_t end;
+ ASSERT_EQ(2, sscanf(lines[i].c_str(), "%" SCNxPTR "-%" SCNxPTR " ", &start, &end))
+ << "Failed to parse line: " << lines[i];
+ // This will never fail on the first line, so no need to do any special checking.
+ ASSERT_GE(start, last_end) << "Overlapping map detected:\n" << lines[i -1] << lines[i];
+ last_start = start;
+ last_end = end;
+ }
+
ASSERT_EQ(0, munmap(p, page_size * 3));
#else
GTEST_LOG_(INFO) << "This test does nothing as it tests an Android specific kernel feature.";
