netfilter: ipv6: nf_defrag: fix NULL deref panic
authorFlorian Westphal <fw@strlen.de>
Tue, 8 Dec 2015 22:35:19 +0000 (23:35 +0100)
committerPablo Neira Ayuso <pablo@netfilter.org>
Wed, 9 Dec 2015 13:26:31 +0000 (14:26 +0100)
commite97ac12859dbf4d3ee0eddb9798867541d1d1e1e
treeedb988527d916389a065d447fbc830870ab82933
parente639f7ab079b5256660018511d87aa34b54f1a9d
netfilter: ipv6: nf_defrag: fix NULL deref panic

Valdis reports NULL deref in nf_ct_frag6_gather.
Problem is bogus use of skb_queue_walk() -- we miss first skb in the list
since we start with head->next instead of head.

In case the element we're looking for was head->next we won't find
a result and then trip over NULL iter.

(defrag uses plain NULL-terminated list rather than one terminated by
 head-of-list-pointer, which is what skb_queue_walk expects).

Fixes: 029f7f3b8701cc7a ("netfilter: ipv6: nf_defrag: avoid/free clone operations")
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
net/ipv6/netfilter/nf_conntrack_reasm.c