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Do not use GetBoolProperty in signal handler

Browse source 
This uses an std::string, which causes a heap allocation, which is not
async-safe.

Test: atest --no-bazel-mode permissive_mte_test
Change-Id: I4bd53d42d9a6a659abe62a964f14c81d9ec059d0
This commit is contained in:
Florian Mayer 2022-09-16 11:25:35 -07:00
parent 61c82abe24
commit 094917deb7
2 changed files with 46 additions and 2 deletions
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19
debuggerd/handler/debuggerd_handler.cpp
View file

@ -24,6 +24,7 @@
#include <sched.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -51,7 +52,6 @@
#include "handler/fallback.h"
using ::android::base::GetBoolProperty;
using ::android::base::ParseBool;
using ::android::base::ParseBoolResult;
using ::android::base::Pipe;
@ -87,10 +87,25 @@ static pid_t __gettid() {
return syscall(__NR_gettid);
}
static bool property_parse_bool(const char* name) {
const prop_info* pi = __system_property_find(name);
if (!pi) return false;
bool cookie = false;
__system_property_read_callback(
pi,
[](void* cookie, const char*, const char* value, uint32_t) {
*reinterpret_cast<bool*>(cookie) = ParseBool(value) == ParseBoolResult::kTrue;
},
&cookie);
return cookie;
}
static bool is_permissive_mte() {
// Environment variable for testing or local use from shell.
char* permissive_env = getenv("MTE_PERMISSIVE");
return GetBoolProperty("persist.sys.mte.permissive", false) ||
// DO NOT REPLACE this with GetBoolProperty. That uses std::string which allocates, so it is
// not async-safe (and this functiong gets used in a signal handler).
return property_parse_bool("persist.sys.mte.permissive") ||
(permissive_env && ParseBool(permissive_env) == ParseBoolResult::kTrue);
}

29
debuggerd/test_permissive_mte/src/com/android/tests/debuggerd/PermissiveMteTest.java
View file

@ -97,4 +97,33 @@ public class PermissiveMteTest extends BaseHostJUnit4Test {
}
assertThat(numberTombstones).isEqualTo(1);
}
@Test
public void testCrashProperty() throws Exception {
String prevValue = getDevice().getProperty("persist.sys.mte.permissive");
if (prevValue == null) {
prevValue = "";
}
assertThat(getDevice().setProperty("persist.sys.mte.permissive", "1")).isTrue();
CommandResult result =
getDevice().executeShellV2Command("/data/local/tmp/mte_crash testCrash " + mUUID);
assertThat(result.getExitCode()).isEqualTo(0);
int numberTombstones = 0;
String[] tombstones = getDevice().getChildren("/data/tombstones");
for (String tombstone : tombstones) {
if (!tombstone.endsWith(".pb")) {
continue;
}
String tombstonePath = "/data/tombstones/" + tombstone;
Tombstone tombstoneProto = parseTombstone(tombstonePath);
if (!tombstoneProto.getCommandLineList().stream().anyMatch(x -> x.contains(mUUID))) {
continue;
}
if (!tombstoneProto.getCommandLineList().stream().anyMatch(x -> x.contains("testCrash"))) {
continue;
}
numberTombstones++;
}
assertThat(numberTombstones).isEqualTo(1);
assertThat(getDevice().setProperty("persist.sys.mte.permissive", prevValue)).isTrue();
}
}