3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Borkmann <dbork...@redhat.com>
[ Upstream commit 3a1c756590633c0e86df606e5c618c190926a0df ]
In tcp_v6_do_rcv() code, when processing pkt options, we soley work
on our skb clone opt_skb that we've created earlier before entering
tcp_rcv_established() on our way. However, only in condition ...
if (np->rxopt.bits.rxtclass)
np->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(skb));
... we work on skb itself. As we extract every other information out
of opt_skb in ipv6_pktoptions path, this seems wrong, since skb can
already be released by tcp_rcv_established() earlier on. When we try
to access it in ipv6_hdr(), we will dereference freed skb.
[ Bug added by commit 4c507d2897bd9b ("net: implement IP_RECVTOS for
IP_PKTOPTIONS") ]
Signed-off-by: Daniel Borkmann <dbork...@redhat.com>
Cc: Eric Dumazet <eric.duma...@gmail.com>
Acked-by: Eric Dumazet <eduma...@google.com>
Acked-by: Jiri Benc <jb...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
net/ipv6/tcp_ipv6.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1571,7 +1571,7 @@ ipv6_pktoptions:
if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit;
if (np->rxopt.bits.rxtclass)
- np->rcv_tclass = ipv6_tclass(ipv6_hdr(skb));
+ np->rcv_tclass = ipv6_tclass(ipv6_hdr(opt_skb));
if (ipv6_opt_accepted(sk, opt_skb)) {
skb_set_owner_r(opt_skb, sk);
opt_skb = xchg(&np->pktoptions, opt_skb);
--
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