This is a note to let you know that I've just added the patch titled
net_sched: check error pointer in tcf_dump_walker()
to the 5.4-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-check-error-pointer-in-tcf_dump_walker.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 29fab1449162184edd9029e4a1efc1f59f66b446
Author: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Date: Fri Oct 2 12:13:34 2020 -0700
net_sched: check error pointer in tcf_dump_walker()
[ Upstream commit 580e4273d7a883ececfefa692c1f96bdbacb99b5 ]
Although we take RTNL on dump path, it is possible to
skip RTNL on insertion path. So the following race condition
is possible:
rtnl_lock() // no rtnl lock
mutex_lock(&idrinfo->lock);
// insert ERR_PTR(-EBUSY)
mutex_unlock(&idrinfo->lock);
tc_dump_action()
rtnl_unlock()
So we have to skip those temporary -EBUSY entries on dump path
too.
Reported-and-tested-by: syzbot+b47bc4f247856fb4d9e1@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together")
Cc: Vlad Buslov <vladbu@xxxxxxxxxxxx>
Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Cc: Jiri Pirko <jiri@xxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 17e5cd9ebd89..75132d0ca887 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -231,6 +231,8 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
index++;
if (index < s_i)
continue;
+ if (IS_ERR(p))
+ continue;
if (jiffy_since &&
time_after(jiffy_since,
