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ipv6: fix possible use-after-free in ip6_xmit()

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In the unlikely case ip6_xmit() has to call skb_realloc_headroom(),
we need to call skb_set_owner_w() before consuming original skb,
otherwise we risk a use-after-free.

Bring IPv6 in line with what we do in IPv4 to fix this.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-09-14 12:02:31 -07:00 committed by David S. Miller
parent a7f38002fb
commit bbd6528d28
1 changed files with 2 additions and 4 deletions
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6
net/ipv6/ip6_output.c
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@ -219,12 +219,10 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
kfree_skb(skb);
return -ENOBUFS;
}
if (skb->sk)
skb_set_owner_w(skb2, skb->sk);
consume_skb(skb);
skb = skb2;
/* skb_set_owner_w() changes sk->sk_wmem_alloc atomically,
* it is safe to call in our context (socket lock not held)
*/
skb_set_owner_w(skb, (struct sock *)sk);
}
if (opt->opt_flen)
ipv6_push_frag_opts(skb, opt, &proto);