Merge "lmkd: Prevent non-main threads being registered or killed by lmkd" into qt-r1-dev (e818cccd) · Commits · e / os / android_system_core

lmkd/lmkd.c

+60 −0

Original line number	Diff line number	Diff line
		@@ -79,6 +79,7 @@
		#define MEMCG_MEMORYSW_USAGE "/dev/memcg/memory.memsw.usage_in_bytes"
		#define ZONEINFO_PATH "/proc/zoneinfo"
		#define MEMINFO_PATH "/proc/meminfo"
		#define PROC_STATUS_TGID_FIELD "Tgid:"
		#define LINE_MAX 128

		/* Android Logger event logtags (see event.logtags) */
		@@ -551,6 +552,49 @@ static inline long get_time_diff_ms(struct timespec *from,
		(to->tv_nsec - from->tv_nsec) / (long)NS_PER_MS;
		}

		static int proc_get_tgid(int pid) {
		char path[PATH_MAX];
		char buf[PAGE_SIZE];
		int fd;
		ssize_t size;
		char *pos;
		int64_t tgid = -1;

		snprintf(path, PATH_MAX, "/proc/%d/status", pid);
		fd = open(path, O_RDONLY \| O_CLOEXEC);
		if (fd < 0) {
		return -1;
		}

		size = read_all(fd, buf, sizeof(buf) - 1);
		if (size < 0) {
		goto out;
		}
		buf[size] = 0;

		pos = buf;
		while (true) {
		pos = strstr(pos, PROC_STATUS_TGID_FIELD);
		/* Stop if TGID tag not found or found at the line beginning */
		if (pos == NULL \|\| pos == buf \|\| pos[-1] == '\n') {
		break;
		}
		pos++;
		}

		if (pos == NULL) {
		goto out;
		}

		pos += strlen(PROC_STATUS_TGID_FIELD);
		while (*pos == ' ') pos++;
		parse_int64(pos, &tgid);

		out:
		close(fd);
		return (int)tgid;
		}

		static void cmd_procprio(LMKD_CTRL_PACKET packet) {
		struct proc *procp;
		char path[80];
		@@ -559,6 +603,7 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
		struct lmk_procprio params;
		bool is_system_server;
		struct passwd *pwdrec;
		int tgid;

		lmkd_pack_get_procprio(packet, &params);

		@@ -568,6 +613,14 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
		return;
		}

		/* Check if registered process is a thread group leader */
		tgid = proc_get_tgid(params.pid);
		if (tgid >= 0 && tgid != params.pid) {
		ALOGE("Attempt to register a task that is not a thread group leader (tid %d, tgid %d)",
		params.pid, tgid);
		return;
		}

		/* gid containing AID_READPROC required */
		/* CAP_SYS_RESOURCE required */
		/* CAP_DAC_OVERRIDE required */
		@@ -1332,6 +1385,7 @@ static int last_killed_pid = -1;
		static int kill_one_process(struct proc* procp, int min_oom_score) {
		int pid = procp->pid;
		uid_t uid = procp->uid;
		int tgid;
		char *taskname;
		int tasksize;
		int r;
		@@ -1345,6 +1399,12 @@ static int kill_one_process(struct proc* procp, int min_oom_score) {
		(void)(min_oom_score);
		#endif

		tgid = proc_get_tgid(pid);
		if (tgid >= 0 && tgid != pid) {
		ALOGE("Possible pid reuse detected (pid %d, tgid %d)!", pid, tgid);
		goto out;
		}

		taskname = proc_get_name(pid);
		if (!taskname) {
		goto out;