Patch "net: neigh: guard against NULL solicit() method" has been added to the 4.4-stable tree

Patch "net: neigh: guard against NULL solicit() method" has been added to the 4.4-stable tree

[gregkh]

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

    net: neigh: guard against NULL solicit() method

to the 4.4-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:
     net-neigh-guard-against-null-solicit-method.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Apr 30 15:46:17 CEST 2017
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 23 Mar 2017 12:39:21 -0700
Subject: net: neigh: guard against NULL solicit() method

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit 48481c8fa16410ffa45939b13b6c53c2ca609e5f ]

Dmitry posted a nice reproducer of a bug triggering in neigh_probe()
when dereferencing a NULL neigh->ops->solicit method.

This can happen for arp_direct_ops/ndisc_direct_ops and similar,
which can be used for NUD_NOARP neighbours (created when dev->header_ops
is NULL). Admin can then force changing nud_state to some other state
that would fire neigh timer.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/neighbour.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -859,7 +859,8 @@ static void neigh_probe(struct neighbour
 	if (skb)
 		skb = skb_clone(skb, GFP_ATOMIC);
 	write_unlock(&neigh->lock);
-	neigh->ops->solicit(neigh, skb);
+	if (neigh->ops->solicit)
+		neigh->ops->solicit(neigh, skb);
 	atomic_inc(&neigh->probes);
 	kfree_skb(skb);
 }


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.4/tcp-clear-saved_syn-in-tcp_disconnect.patch
queue-4.4/net-packet-fix-overflow-in-check-for-tp_frame_nr.patch
queue-4.4/net-packet-fix-overflow-in-check-for-tp_reserve.patch
queue-4.4/net-neigh-guard-against-null-solicit-method.patch