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platform_system_core
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crash_dump: remove unneeded/faulty checks. 

We already check our /proc/`getppid()` fd every time we attach a thread, so
these were unneeded at best. The one that happened after dropping
capabilities was actively wrong, though, because /proc/pid access
checks happen on every operation. (only on some kernels?)

Also, add a check that getppid() doesn't change after opening
/proc/getppid().

Bug: http://b/35241370
Test: debuggerd -b `pidof com.android.bluetooth`
Change-Id: I807439d8c2afd027f3c382face50167a8a7946c4
This commit is contained in:
Josh Gao 2017-02-16 19:17:28 -08:00
parent 325eeebc47
commit 2a18b822d5
1 changed files with 5 additions and 14 deletions
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19
debuggerd/crash_dump.cpp
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@ -219,17 +219,6 @@ static void drop_capabilities() {
}
}
static void check_process(int proc_fd, pid_t expected_pid) {
android::procinfo::ProcessInfo proc_info;
if (!android::procinfo::GetProcessInfoFromProcPidFd(proc_fd, &proc_info)) {
LOG(FATAL) << "failed to fetch process info";
}
if (proc_info.pid != expected_pid) {
LOG(FATAL) << "pid mismatch: expected " << expected_pid << ", actual " << proc_info.pid;
}
}
int main(int argc, char** argv) {
pid_t target = getppid();
bool tombstoned_connected = false;
@ -282,6 +271,11 @@ int main(int argc, char** argv) {
PLOG(FATAL) << "failed to open " << target_proc_path;
}
// Make sure our parent didn't die.
if (getppid() != target) {
PLOG(FATAL) << "parent died";
}
// Reparent ourselves to init, so that the signal handler can waitpid on the
// original process to avoid leaving a zombie for non-fatal dumps.
pid_t forkpid = fork();
@ -294,8 +288,6 @@ int main(int argc, char** argv) {
// Die if we take too long.
alarm(20);
check_process(target_proc_fd, target);
std::string attach_error;
// Seize the main thread.
@ -337,7 +329,6 @@ int main(int argc, char** argv) {
// Drop our capabilities now that we've attached to the threads we care about.
drop_capabilities();
check_process(target_proc_fd, target);
LOG(INFO) << "obtaining output fd from tombstoned";
tombstoned_connected = tombstoned_connect(target, &tombstoned_socket, &output_fd);