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authorFlorian Westphal <fw@strlen.de>2018-07-09 14:43:38 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2018-07-09 19:04:12 +0300
commit84379c9afe011020e797e3f50a662b08a6355dcf (patch)
treea79259618f88d26e90f3e50cf1d4823852b90365 /net/ipv6
parent2045cdfa1b40d66f126f3fd05604fc7c754f0022 (diff)
downloadlinux-84379c9afe011020e797e3f50a662b08a6355dcf.tar.xz
netfilter: ipv6: nf_defrag: drop skb dst before queueing
Eric Dumazet reports: Here is a reproducer of an annoying bug detected by syzkaller on our production kernel [..] ./b78305423 enable_conntrack Then : sleep 60 dmesg | tail -10 [ 171.599093] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 181.631024] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 191.687076] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 201.703037] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 211.711072] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 221.959070] unregister_netdevice: waiting for lo to become free. Usage count = 2 Reproducer sends ipv6 fragment that hits nfct defrag via LOCAL_OUT hook. skb gets queued until frag timer expiry -- 1 minute. Normally nf_conntrack_reasm gets called during prerouting, so skb has no dst yet which might explain why this wasn't spotted earlier. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Reported-by: John Sperbeck <jsperbeck@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Tested-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/netfilter/nf_conntrack_reasm.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index a452d99c9f52..e4d9e6976d3c 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -585,6 +585,8 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user)
fq->q.meat == fq->q.len &&
nf_ct_frag6_reasm(fq, skb, dev))
ret = 0;
+ else
+ skb_dst_drop(skb);
out_unlock:
spin_unlock_bh(&fq->q.lock);