Patch "af_unix: Revert 'lock_interruptible' in stream receive code" has been added to the 3.10-stable tree

[<gregkh@linuxfoundation.org>]

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

    af_unix: Revert 'lock_interruptible' in stream receive code

to the 3.10-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-revert-lock_interruptible-in-stream-receive-code.patch
and it can be found in the queue-3.10 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 Mon Jan 18 21:18:36 PST 2016
From: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Date: Wed, 16 Dec 2015 20:09:25 +0000
Subject: af_unix: Revert 'lock_interruptible' in stream receive code
Status: RO
Content-Length: 2049
Lines: 58

From: Rainer Weikusat <rweikusat@mobileactivedefense.com>

[ Upstream commit 3822b5c2fc62e3de8a0f33806ff279fb7df92432 ]

With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM
receive code was changed from using mutex_lock(&u->readlock) to
mutex_lock_interruptible(&u->readlock) to prevent signals from being
delayed for an indefinite time if a thread sleeping on the mutex
happened to be selected for handling the signal. But this was never a
problem with the stream receive code (as opposed to its datagram
counterpart) as that never went to sleep waiting for new messages with the
mutex held and thus, wouldn't cause secondary readers to block on the
mutex waiting for the sleeping primary reader. As the interruptible
locking makes the code more complicated in exchange for no benefit,
change it back to using mutex_lock.

Signed-off-by: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/unix/af_unix.c |   13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1934,14 +1934,7 @@ static int unix_dgram_recvmsg(struct kio
 	if (flags&MSG_OOB)
 		goto out;
 
-	err = mutex_lock_interruptible(&u->readlock);
-	if (unlikely(err)) {
-		/* recvmsg() in non blocking mode is supposed to return -EAGAIN
-		 * sk_rcvtimeo is not honored by mutex_lock_interruptible()
-		 */
-		err = noblock ? -EAGAIN : -ERESTARTSYS;
-		goto out;
-	}
+	mutex_lock(&u->readlock);
 
 	skip = sk_peek_offset(sk, flags);
 
@@ -2133,12 +2126,12 @@ again:
 
 			timeo = unix_stream_data_wait(sk, timeo, last);
 
-			if (signal_pending(current)
-			    ||  mutex_lock_interruptible(&u->readlock)) {
+			if (signal_pending(current)) {
 				err = sock_intr_errno(timeo);
 				goto out;
 			}
 
+			mutex_lock(&u->readlock);
 			continue;
  unlock:
 			unix_state_unlock(sk);


Patches currently in stable-queue which might be from rweikusat@mobileactivedefense.com are

queue-3.10/unix-avoid-use-after-free-in-ep_remove_wait_queue.patch
queue-3.10/af_unix-revert-lock_interruptible-in-stream-receive-code.patch