Patch "scsi: scsi_dh_alua: Fix a reference counting bug" has been added to the 4.8-stable tree

Patch "scsi: scsi_dh_alua: Fix a reference counting bug" has been added to the 4.8-stable tree

[gregkh]

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

    scsi: scsi_dh_alua: Fix a reference counting bug

to the 4.8-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:
     scsi-scsi_dh_alua-fix-a-reference-counting-bug.patch
and it can be found in the queue-4.8 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 df3d422cbac685da882e4c239dfda07de33d431b Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Tue, 1 Nov 2016 08:19:57 -0600
Subject: scsi: scsi_dh_alua: Fix a reference counting bug

From: Bart Van Assche <bart.vanassche@sandisk.com>

commit df3d422cbac685da882e4c239dfda07de33d431b upstream.

The code at the end of alua_rtpg_work() is as follows:

	scsi_device_put(sdev);
	kref_put(&pg->kref, release_port_group);

In other words, alua_rtpg_queue() must hold an sdev reference and a pg
reference before queueing rtpg work. If no rtpg work is queued no
additional references should be held when alua_rtpg_queue() returns. If
no rtpg work is queued, ensure that alua_rtpg_queue() only gives up the
sdev reference if that reference was obtained by the same
alua_rtpg_queue() call.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reported-by: Tang Junhui <tang.junhui@zte.com.cn>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Tang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/device_handler/scsi_dh_alua.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -890,6 +890,7 @@ static void alua_rtpg_queue(struct alua_
 		/* Do not queue if the worker is already running */
 		if (!(pg->flags & ALUA_PG_RUNNING)) {
 			kref_get(&pg->kref);
+			sdev = NULL;
 			start_queue = 1;
 		}
 	}
@@ -901,7 +902,8 @@ static void alua_rtpg_queue(struct alua_
 	if (start_queue &&
 	    !queue_delayed_work(alua_wq, &pg->rtpg_work,
 				msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS))) {
-		scsi_device_put(sdev);
+		if (sdev)
+			scsi_device_put(sdev);
 		kref_put(&pg->kref, release_port_group);
 	}
 }


Patches currently in stable-queue which might be from bart.vanassche@sandisk.com are

queue-4.8/scsi-scsi_dh_alua-fix-a-reference-counting-bug.patch