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netfilter: ipv6: fix use-after-free Write in nf_nat_ipv6_manip_pkt

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commit b078556aecd791b0e5cb3a59f4c3a14273b52121 upstream.

l4proto->manip_pkt() can cause reallocation of skb head so pointer
to the ipv6 header must be reloaded.

Reported-and-tested-by: <syzbot+10005f4292fc9cc89de7@syzkaller.appspotmail.com>
Fixes: 58a317f1061c89 ("netfilter: ipv6: add IPv6 NAT support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Florian Westphal 2018-02-19 08:10:17 +01:00 committed by Greg Kroah-Hartman
parent 2d7e070039
commit 39f154faec
1 changed files with 4 additions and 0 deletions
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4
net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
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@ -99,6 +99,10 @@ static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
!l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv6, iphdroff, hdroff,
target, maniptype))
return false;
/* must reload, offset might have changed */
ipv6h = (void *)skb->data + iphdroff;
manip_addr:
if (maniptype == NF_NAT_MANIP_SRC)
ipv6h->saddr = target->src.u3.in6;