[3.19.y-ckt stable] Patch "unix/caif: sk_socket can disappear when state is unlocked" has been added to staging queue

[Kamal Mostafa]

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

    unix/caif: sk_socket can disappear when state is unlocked

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-ckt2.

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 2c556e1710d066c6ae8c8716c388b667e0c78658 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn at android.com>
Date: Tue, 26 May 2015 08:22:19 -0700
Subject: unix/caif: sk_socket can disappear when state is unlocked

[ Upstream commit b48732e4a48d80ed4a14812f0bab09560846514e ]

got a rare NULL pointer dereference in clear_bit

Signed-off-by: Mark Salyzyn <salyzyn at android.com>
Acked-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
----
v2: switch to sock_flag(sk, SOCK_DEAD) and added net/caif/caif_socket.c
v3: return -ECONNRESET in upstream caller of wait function for SOCK_DEAD
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/caif/caif_socket.c | 8 ++++++++
 net/unix/af_unix.c     | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index a6e2da0..982101c 100644
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -330,6 +330,10 @@ static long caif_stream_data_wait(struct sock *sk, long timeo)
 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
 		lock_sock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
 		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
 	}

@@ -374,6 +378,10 @@ static int caif_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		struct sk_buff *skb;

 		lock_sock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
 		skb = skb_dequeue(&sk->sk_receive_queue);
 		caif_check_flow_release(sk);

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8e1b102..a8b4284 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1898,6 +1898,10 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
 		unix_state_unlock(sk);
 		timeo = freezable_schedule_timeout(timeo);
 		unix_state_lock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
 		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
 	}

@@ -1962,6 +1966,10 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		struct sk_buff *skb, *last;

 		unix_state_lock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
 		last = skb = skb_peek(&sk->sk_receive_queue);
 again:
 		if (skb == NULL) {
--
1.9.1