Patch "dm rq: cope with DM device destruction while in dm_old_request_fn()" has been added to the 4.9-stable tree

Patch "dm rq: cope with DM device destruction while in dm_old_request_fn()" has been added to the 4.9-stable tree

[gregkh]

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

    dm rq: cope with DM device destruction while in dm_old_request_fn()

to the 4.9-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:
     dm-rq-cope-with-dm-device-destruction-while-in-dm_old_request_fn.patch
and it can be found in the queue-4.9 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 4087a1fffe38106e10646606a27f10d40451862d Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Wed, 25 Jan 2017 16:24:52 +0100
Subject: dm rq: cope with DM device destruction while in dm_old_request_fn()

From: Mike Snitzer <snitzer@redhat.com>

commit 4087a1fffe38106e10646606a27f10d40451862d upstream.

Fixes a crash in dm_table_find_target() due to a NULL struct dm_table
being passed from dm_old_request_fn() that races with DM device
destruction.

Reported-by: artem@flashgrid.io
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/dm-rq.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -804,6 +804,10 @@ static void dm_old_request_fn(struct req
 		int srcu_idx;
 		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 
+		if (unlikely(!map)) {
+			dm_put_live_table(md, srcu_idx);
+			return;
+		}
 		ti = dm_table_find_target(map, pos);
 		dm_put_live_table(md, srcu_idx);
 	}


Patches currently in stable-queue which might be from snitzer@redhat.com are

queue-4.9/dm-rq-cope-with-dm-device-destruction-while-in-dm_old_request_fn.patch