This is a note to let you know that I've just added the patch titled
xen/blkback: fix reference counting
to the 3.12-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-blkback-fix-reference-counting.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ea5ec76d76da9279d12027c1828544c5ccbe7932 Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Date: Thu, 5 Sep 2013 13:00:14 +0200
Subject: xen/blkback: fix reference counting
From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
commit ea5ec76d76da9279d12027c1828544c5ccbe7932 upstream.
If the permission check fails, we drop a reference to the blkif without
having taken it in the first place. The bug was introduced in commit
604c499cbbcc3d5fe5fb8d53306aa0fae1990109 (xen/blkback: Check device
permissions before allowing OP_DISCARD).
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/xen-blkback/blkback.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -887,6 +887,8 @@ static int dispatch_discard_io(struct xe
unsigned long secure;
struct phys_req preq;
+ xen_blkif_get(blkif);
+
preq.sector_number = req->u.discard.sector_number;
preq.nr_sects = req->u.discard.nr_sectors;
@@ -899,7 +901,6 @@ static int dispatch_discard_io(struct xe
}
blkif->st_ds_req++;
- xen_blkif_get(blkif);
secure = (blkif->vbd.discard_secure &&
(req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
BLKDEV_DISCARD_SECURE : 0;
Patches currently in stable-queue which might be from vegard.nossum@xxxxxxxxxx are
queue-3.12/xen-blkback-fix-reference-counting.patch
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