[v6,10/16] kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve
diff mbox series

Message ID AM6PR03MB5170FFDE1D7BF09DD2663EDEE4F50@AM6PR03MB5170.eurprd03.prod.outlook.com
State New
Headers show
Series
  • Infrastructure to allow fixing exec deadlocks
Related show

Commit Message

Bernd Edlinger March 20, 2020, 8:27 p.m. UTC
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 <bernd.edlinger@hotmail.de>
---
 kernel/kcmp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Christian Brauner March 25, 2020, 3:41 p.m. UTC | #1
On Fri, Mar 20, 2020 at 09:27:05PM +0100, Bernd Edlinger wrote:
> 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 <bernd.edlinger@hotmail.de>

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

Patch
diff mbox series

diff --git a/kernel/kcmp.c b/kernel/kcmp.c
index a0e3d7a..b3ff928 100644
--- a/kernel/kcmp.c
+++ b/kernel/kcmp.c
@@ -173,8 +173,8 @@  static int kcmp_epoll_target(struct task_struct *task1,
 	/*
 	 * 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 @@  static int kcmp_epoll_target(struct task_struct *task1,
 	}
 
 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);