Patch "xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)" has been added to the 4.1-stable tree

[<gregkh@linuxfoundation.org>]

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

    xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)

to the 4.1-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:
     xen-blkfront-check-for-null-drvdata-in-blkback_changed-xenbusstateclosing.patch
and it can be found in the queue-4.1 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 a54c8f0f2d7df525ff997e2afe71866a1a013064 Mon Sep 17 00:00:00 2001
From: Cathy Avery <cathy.avery@oracle.com>
Date: Fri, 2 Oct 2015 09:35:01 -0400
Subject: xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)

From: Cathy Avery <cathy.avery@oracle.com>

commit a54c8f0f2d7df525ff997e2afe71866a1a013064 upstream.

xen-blkfront will crash if the check to talk_to_blkback()
in blkback_changed()(XenbusStateInitWait) returns an error.
The driver data is freed and info is set to NULL. Later during
the close process via talk_to_blkback's call to xenbus_dev_fatal()
the null pointer is passed to and dereference in blkfront_closing.

Signed-off-by: Cathy Avery <cathy.avery@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/xen-blkfront.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1925,7 +1925,8 @@ static void blkback_changed(struct xenbu
 			break;
 		/* Missed the backend's Closing state -- fallthrough */
 	case XenbusStateClosing:
-		blkfront_closing(info);
+		if (info)
+			blkfront_closing(info);
 		break;
 	}
 }


Patches currently in stable-queue which might be from cathy.avery@oracle.com are

queue-4.1/xen-blkfront-check-for-null-drvdata-in-blkback_changed-xenbusstateclosing.patch