Patch "af_unix: take receive queue lock while appending new skb" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

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

    af_unix: take receive queue lock while appending new skb

to the 4.2-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:
     af_unix-take-receive-queue-lock-while-appending-new-skb.patch
and it can be found in the queue-4.2 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 Fri Dec 11 11:38:35 EST 2015
From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Tue, 17 Nov 2015 15:10:59 +0100
Subject: af_unix: take receive queue lock while appending new skb

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ Upstream commit a3a116e04cc6a94d595ead4e956ab1bc1d2f4746 ]

While possibly in future we don't necessarily need to use
sk_buff_head.lock this is a rather larger change, as it affects the
af_unix fd garbage collector, diag and socket cleanups. This is too much
for a stable patch.

For the time being grab sk_buff_head.lock without disabling bh and irqs,
so don't use locked skb_queue_tail.

Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support")
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reported-by: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/unix/af_unix.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1812,8 +1812,11 @@ alloc_skb:
 	skb->truesize += size;
 	atomic_add(size, &sk->sk_wmem_alloc);
 
-	if (newskb)
+	if (newskb) {
+		spin_lock(&other->sk_receive_queue.lock);
 		__skb_queue_tail(&other->sk_receive_queue, newskb);
+		spin_unlock(&other->sk_receive_queue.lock);
+	}
 
 	unix_state_unlock(other);
 	mutex_unlock(&unix_sk(other)->readlock);


Patches currently in stable-queue which might be from hannes@stressinduktion.org are

queue-4.2/ipv6-add-complete-rcu-protection-around-np-opt.patch
queue-4.2/ipv6-check-rt-dst.from-for-the-dst_nocache-route.patch
queue-4.2/af-unix-passcred-support-for-sendpage.patch
queue-4.2/af_unix-don-t-append-consumed-skbs-to-sk_receive_queue.patch
queue-4.2/ipv6-avoid-creating-rtf_cache-from-a-rt-that-is-not-managed-by-fib6-tree.patch
queue-4.2/net-scm-fix-pax-detected-msg_controllen-overflow-in-scm_detach_fds.patch
queue-4.2/ipv6-check-expire-on-dst_nocache-route.patch
queue-4.2/af-unix-fix-use-after-free-with-concurrent-readers-while-splicing.patch
queue-4.2/ip_tunnel-disable-preemption-when-updating-per-cpu-tstats.patch
queue-4.2/af_unix-take-receive-queue-lock-while-appending-new-skb.patch