Patch "ipv6: tcp: add a missing tcp_v6_restore_cb()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ipv6: tcp: add a missing tcp_v6_restore_cb()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ipv6-tcp-add-a-missing-tcp_v6_restore_cb.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Dumazet <[email protected]>
Date: Sun, 5 Feb 2017 20:23:22 -0800
Subject: ipv6: tcp: add a missing tcp_v6_restore_cb()

From: Eric Dumazet <[email protected]>

[ Upstream commit ebf6c9cb23d7e56eec8575a88071dec97ad5c6e2 ]

Dmitry reported use-after-free in ip6_datagram_recv_specific_ctl()

A similar bug was fixed in commit 8ce48623f0cf ("ipv6: tcp: restore IP6CB for pktoptions skbs"), but I missed another spot.

tcp_v6_syn_recv_sock() can indeed set np->pktoptions from ireq->pktopts

---
 net/ipv6/tcp_ipv6.c |   24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

@@ -987,6 +987,16 @@ drop:
 	return 0; /* don't send reset */
 }
 
+static void tcp_v6_restore_cb(struct sk_buff *skb)
+{
+	/* We need to move header back to the beginning if xfrm6_policy_check()
+	 * and tcp_v6_fill_cb() are going to be called again.
+	 * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there.
+	 */
+	memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
+		sizeof(struct inet6_skb_parm));
+}
+
 static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
 					 struct request_sock *req,
 					 struct dst_entry *dst,

@@ -1178,8 +1188,10 @@ static struct sock *tcp_v6_syn_recv_sock
 						      sk_gfp_mask(sk, GFP_ATOMIC));
 			consume_skb(ireq->pktopts);
 			ireq->pktopts = NULL;
-			if (newnp->pktoptions)
+			if (newnp->pktoptions) {
+				tcp_v6_restore_cb(newnp->pktoptions);
 				skb_set_owner_r(newnp->pktoptions, newsk);
+			}
 		}
 	}
 

@@ -1194,16 +1206,6 @@ out:
 	return NULL;
 }
 
-static void tcp_v6_restore_cb(struct sk_buff *skb)
-{
-	/* We need to move header back to the beginning if xfrm6_policy_check()
-	 * and tcp_v6_fill_cb() are going to be called again.
-	 * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there.
-	 */
-	memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
-		sizeof(struct inet6_skb_parm));
-}
-
 /* The socket must have it's spinlock held when we get
  * here, unless it is a TCP_LISTEN socket.
  *

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ipv6-pointer-math-error-in-ip6_tnl_parse_tlv_enc_lim.patch queue-4.9/netlabel-out-of-bound-access-in-cipso_v4_validate.patch queue-4.9/packet-round-up-linear-to-header-len.patch queue-4.9/tun-read-vnet_hdr_sz-once.patch queue-4.9/ipv6-fix-ip6_tnl_parse_tlv_enc_lim.patch queue-4.9/l2tp-do-not-use-udp_ioctl.patch queue-4.9/tcp-fix-0-divide-in-__tcp_select_window.patch queue-4.9/can-fix-kernel-panic-at-security_sock_rcv_skb.patch queue-4.9/net-introduce-device-min_header_len.patch queue-4.9/macvtap-read-vnet_hdr_size-once.patch queue-4.9/tcp-avoid-infinite-loop-in-tcp_splice_read.patch queue-4.9/mlx4-invoke-softirqs-after-napi_reschedule.patch queue-4.9/ipv6-tcp-add-a-missing-tcp_v6_restore_cb.patch queue-4.9/ipv4-keep-skb-dst-around-in-presence-of-ip-options.patch queue-4.9/net-use-a-work-queue-to-defer-net_disable_timestamp-work.patch queue-4.9/ip6_gre-fix-ip6gre_err-invalid-reads.patch