kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve

This changes kcmp_epoll_target to use the new exec_update_mutex instead of cred_guard_mutex. This should be safe, as the credentials are only used for reading, and furthermore ->mm and ->sighand are updated on execve, but only under the new exec_update_mutex. Signed-off-by: Bernd Edlinger <[email protected]> Signed-off-by: Eric W. Biederman <[email protected]>
ambv · Mar 25, 2020 · 454e312 · 454e312
1 parent aa884c1
commit 454e312
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/kernel/kcmp.c b/kernel/kcmp.c
@@ -173,8 +173,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
 	/*
 	 * One should have enough rights to inspect task details.
 	 */
-	ret = kcmp_lock(&task1->signal->cred_guard_mutex,
-			&task2->signal->cred_guard_mutex);
+	ret = kcmp_lock(&task1->signal->exec_update_mutex,
+			&task2->signal->exec_update_mutex);
 	if (ret)
 		goto err;
 	if (!ptrace_may_access(task1, PTRACE_MODE_READ_REALCREDS) ||
@@ -229,8 +229,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
 	}
 
 err_unlock:
-	kcmp_unlock(&task1->signal->cred_guard_mutex,
-		    &task2->signal->cred_guard_mutex);
+	kcmp_unlock(&task1->signal->exec_update_mutex,
+		    &task2->signal->exec_update_mutex);
 err:
 	put_task_struct(task1);
 	put_task_struct(task2);