This is a note to let you know that I've just added the patch titled
net: sched: fix crash when deleting secondary chains
to the 4.14-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-fix-crash-when-deleting-secondary-chains.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d7aa04a5e82b4f254d306926c81eae8df69e5200 Mon Sep 17 00:00:00 2001
From: Roman Kapl <code@xxxxxxxx>
Date: Mon, 20 Nov 2017 22:21:13 +0100
Subject: net: sched: fix crash when deleting secondary chains
From: Roman Kapl <code@xxxxxxxx>
commit d7aa04a5e82b4f254d306926c81eae8df69e5200 upstream.
If you flush (delete) a filter chain other than chain 0 (such as when
deleting the device), the kernel may run into a use-after-free. The
chain refcount must not be decremented unless we are sure we are done
with the chain.
To reproduce the bug, run:
ip link add dtest type dummy
tc qdisc add dev dtest ingress
tc filter add dev dtest chain 1 parent ffff: flower
ip link del dtest
Introduced in: commit f93e1cdcf42c ("net/sched: fix filter flushing"),
but unless you have KAsan or luck, you won't notice it until
commit 0dadc117ac8b ("cls_flower: use tcf_exts_get_net() before call_rcu()")
Fixes: f93e1cdcf42c ("net/sched: fix filter flushing")
Acked-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: Roman Kapl <code@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/cls_api.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -197,14 +197,15 @@ static struct tcf_chain *tcf_chain_creat
static void tcf_chain_flush(struct tcf_chain *chain)
{
- struct tcf_proto *tp;
+ struct tcf_proto *tp = rtnl_dereference(chain->filter_chain);
if (chain->p_filter_chain)
RCU_INIT_POINTER(*chain->p_filter_chain, NULL);
- while ((tp = rtnl_dereference(chain->filter_chain)) != NULL) {
+ while (tp) {
RCU_INIT_POINTER(chain->filter_chain, tp->next);
- tcf_chain_put(chain);
tcf_proto_destroy(tp);
+ tp = rtnl_dereference(chain->filter_chain);
+ tcf_chain_put(chain);
}
}
Patches currently in stable-queue which might be from code@xxxxxxxx are
queue-4.14/net-sched-crash-on-blocks-with-goto-chain-action.patch
queue-4.14/net-sched-fix-crash-when-deleting-secondary-chains.patch