| From | Kamal Mostafa <> | Subject | [PATCH 3.8 080/152] xen/blkback: fix reference counting | Date | Fri, 6 Dec 2013 15:10:04 -0800 |
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3.8.13.14 -stable review patch. If anyone has any objections, please let me know.
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From: Vegard Nossum <vegard.nossum@oracle.com>
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@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/block/xen-blkback/blkback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index bdee5f8..088f012 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -658,6 +658,8 @@ static int dispatch_discard_io(struct xen_blkif *blkif, 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; @@ -670,7 +672,6 @@ static int dispatch_discard_io(struct xen_blkif *blkif, } blkif->st_ds_req++; - xen_blkif_get(blkif); secure = (blkif->vbd.discard_secure && (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ? BLKDEV_DISCARD_SECURE : 0; -- 1.8.3.2
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