This is a note to let you know that I've just added the patch titled
netfilter: ctnetlink: fix incorrect nf_ct_put during hash resize
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: netfilter-ctnetlink-fix-incorrect-nf_ct_put-during-hash-resize.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: Liping Zhang zlpnobody@gmail.com Date: Sun, 21 May 2017 07:22:49 +0800 Subject: netfilter: ctnetlink: fix incorrect nf_ct_put during hash resize
From: Liping Zhang zlpnobody@gmail.com
[ Upstream commit fefa92679dbe0c613e62b6c27235dcfbe9640ad1 ]
If nf_conntrack_htable_size was adjusted by the user during the ct dump operation, we may invoke nf_ct_put twice for the same ct, i.e. the "last" ct. This will cause the ct will be freed but still linked in hash buckets.
It's very easy to reproduce the problem by the following commands: # while : ; do echo $RANDOM > /proc/sys/net/netfilter/nf_conntrack_buckets done # while : ; do conntrack -L done # iperf -s 127.0.0.1 & # iperf -c 127.0.0.1 -P 60 -t 36000
After a while, the system will hang like this: NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [bash:20184] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [iperf:20382] ...
So at last if we find cb->args[1] is equal to "last", this means hash resize happened, then we can set cb->args[1] to 0 to fix the above issue.
Fixes: d205dc40798d ("[NETFILTER]: ctnetlink: fix deadlock in table dumping") Signed-off-by: Liping Zhang zlpnobody@gmail.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_conntrack_netlink.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -887,8 +887,13 @@ restart: } out: local_bh_enable(); - if (last) + if (last) { + /* nf ct hash resize happened, now clear the leftover. */ + if ((struct nf_conn *)cb->args[1] == last) + cb->args[1] = 0; + nf_ct_put(last); + }
return skb->len; }
Patches currently in stable-queue which might be from zlpnobody@gmail.com are
queue-4.4/netfilter-ctnetlink-fix-incorrect-nf_ct_put-during-hash-resize.patch