This is a note to let you know that I've just added the patch titled
net: sched: consistently use rcu_replace_pointer() in taprio_change()
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-consistently-use-rcu_replace_pointer-in-ta.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bad064772c96d27592aabf9e0430ef13ce221fbf
Author: Dmitry Antipov <dmantipov@xxxxxxxxx>
Date: Wed Sep 4 14:54:01 2024 +0300
net: sched: consistently use rcu_replace_pointer() in taprio_change()
[ Upstream commit d5c4546062fd6f5dbce575c7ea52ad66d1968678 ]
According to Vinicius (and carefully looking through the whole
https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa
once again), txtime branch of 'taprio_change()' is not going to
race against 'advance_sched()'. But using 'rcu_replace_pointer()'
in the former may be a good idea as well.
Suggested-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index cc2df9f8c14a6..8498d0606b248 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1952,7 +1952,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
goto unlock;
}
- rcu_assign_pointer(q->admin_sched, new_admin);
+ /* Not going to race against advance_sched(), but still */
+ admin = rcu_replace_pointer(q->admin_sched, new_admin,
+ lockdep_rtnl_is_held());
if (admin)
call_rcu(&admin->rcu, taprio_free_sched_cb);
} else {
