[3.19.y-ckt stable] Patch "net: avoid NULL deref in inet_ctl_sock_destroy()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    net: avoid NULL deref in inet_ctl_sock_destroy()

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 016994ff735c28354e08ef4bc12e06aae8c5f87e Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet at google.com>
Date: Mon, 2 Nov 2015 07:50:07 -0800
Subject: net: avoid NULL deref in inet_ctl_sock_destroy()

[ Upstream commit 8fa677d2706d325d71dab91bf6e6512c05214e37 ]

Under low memory conditions, tcp_sk_init() and icmp_sk_init()
can both iterate on all possible cpus and call inet_ctl_sock_destroy(),
with eventual NULL pointer.

Signed-off-by: Eric Dumazet <edumazet at google.com>
Reported-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 include/net/inet_common.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/inet_common.h b/include/net/inet_common.h
index b2828a0..a7d812d 100644
--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -42,7 +42,8 @@ int inet_recv_error(struct sock *sk, struct msghdr *msg, int len,

 static inline void inet_ctl_sock_destroy(struct sock *sk)
 {
-	sk_release_kernel(sk);
+	if (sk)
+		sk_release_kernel(sk);
 }

 #endif
--
1.9.1