From: Arnaldo Carvalho de Melo <acme@kernel.org>
Date: Mon, 28 Nov 2016 15:36:58 +0000 (-0300)
Subject: GSO: Reload iph after pskb_may_pull
X-Git-Tag: v4.8.14~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=17941a9d6409e03b41d5757b36cb8a273ce082d8;p=thirdparty%2Fkernel%2Fstable.git

GSO: Reload iph after pskb_may_pull

[ Upstream commit a510887824171ad260cc4a2603396c6247fdd091 ]

As it may get stale and lead to use after free.

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Alexander Duyck <aduyck@mirantis.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Fixes: cbc53e08a793 ("GSO: Add GSO type for fixed IPv4 ID")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index eebbc0f2baa8d..ed22af67c58a5 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1237,7 +1237,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 		fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
 
 		/* fixed ID is invalid if DF bit is not set */
-		if (fixedid && !(iph->frag_off & htons(IP_DF)))
+		if (fixedid && !(ip_hdr(skb)->frag_off & htons(IP_DF)))
 			goto out;
 	}