proc: Use new infrastructure to fix deadlocks in execve (2db9dbf7) · Commits · 戴 / test

This changes lock_trace to use the new exec_update_mutex instead of cred_guard_mutex. This fixes possible deadlocks when the trace is accessing /proc/$pid/stack for instance. This should be safe, as the credentials are only used for reading, and task->mm is updated on execve under the new exec_update_mutex. Signed-off-by:

Bernd Edlinger <bernd.edlinger@hotmail.de> Signed-off-by:

Eric W. Biederman <ebiederm@xmission.com>

fs/proc/base.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -405,11 +405,11 @@ print0:

		static int lock_trace(struct task_struct *task)
		{
		int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
		int err = mutex_lock_killable(&task->signal->exec_update_mutex);
		if (err)
		return err;
		if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
		mutex_unlock(&task->signal->cred_guard_mutex);
		mutex_unlock(&task->signal->exec_update_mutex);
		return -EPERM;
		}
		return 0;
		@@ -417,7 +417,7 @@ static int lock_trace(struct task_struct *task)

		static void unlock_trace(struct task_struct *task)
		{
		mutex_unlock(&task->signal->cred_guard_mutex);
		mutex_unlock(&task->signal->exec_update_mutex);
		}

		#ifdef CONFIG_STACKTRACE

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