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debuggerd: don't leave a zombie child if crash_dump is killed. 

If crash_dump dies before it gets a chance to write to the pipe we use
to let the debugged-process know that it successfully started, we
weren't cleaning up the child we fork to start it, leaving a zombie
child.

Bug: http://b/152119184
Test: debuggerd_test
Change-Id: Id01cc05f693995e9998941774f74ab8e3d8b4d8a
This commit is contained in:
Josh Gao 2020-04-10 10:09:39 -07:00
parent 89cce05891
commit c40a7515eb
1 changed files with 29 additions and 22 deletions
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51
debuggerd/handler/debuggerd_handler.cpp
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@ -417,23 +417,28 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
// us to fork off a process to read memory from.
char buf[4];
rc = TEMP_FAILURE_RETRY(read(input_read.get(), &buf, sizeof(buf)));
if (rc == -1) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "read of IPC pipe failed: %s", strerror(errno));
return 1;
} else if (rc == 0) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper failed to exec");
return 1;
} else if (rc != 1) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc",
"read of IPC pipe returned unexpected value: %zd", rc);
return 1;
} else if (buf[0] != '\1') {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper reported failure");
return 1;
}
// crash_dump is ptracing us, fork off a copy of our address space for it to use.
create_vm_process();
bool success = false;
if (rc == 1 && buf[0] == '\1') {
// crash_dump successfully started, and is ptracing us.
// Fork off a copy of our address space for it to use.
create_vm_process();
success = true;
} else {
// Something went wrong, log it.
if (rc == -1) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "read of IPC pipe failed: %s",
strerror(errno));
} else if (rc == 0) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc",
"crash_dump helper failed to exec, or was killed");
} else if (rc != 1) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc",
"read of IPC pipe returned unexpected value: %zd", rc);
} else if (buf[0] != '\1') {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper reported failure");
}
}
// Don't leave a zombie child.
int status;
@ -444,14 +449,16 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
async_safe_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper crashed or stopped");
}
if (thread_info->siginfo->si_signo != BIONIC_SIGNAL_DEBUGGER) {
// For crashes, we don't need to minimize pause latency.
// Wait for the dump to complete before having the process exit, to avoid being murdered by
// ActivityManager or init.
TEMP_FAILURE_RETRY(read(input_read, &buf, sizeof(buf)));
if (success) {
if (thread_info->siginfo->si_signo != BIONIC_SIGNAL_DEBUGGER) {
// For crashes, we don't need to minimize pause latency.
// Wait for the dump to complete before having the process exit, to avoid being murdered by
// ActivityManager or init.
TEMP_FAILURE_RETRY(read(input_read, &buf, sizeof(buf)));
}
}
return 0;
return success ? 0 : 1;
}
static void resend_signal(siginfo_t* info) {