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    Subject[PATCH 4.9 60/86] netfilter: ipv6: fix use-after-free Write in nf_nat_ipv6_manip_pkt
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Florian Westphal <fw@strlen.de>

    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>

    ---
    net/ipv6/netfilter/nf_nat_l3proto_ipv6.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
    +++ b/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c
    @@ -99,6 +99,10 @@ static bool nf_nat_ipv6_manip_pkt(struct
    !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;

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