3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vegard Nossum <vegard.nos...@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 <jbeul...@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Signed-off-by: Vegard Nossum <vegard.nos...@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
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
@@ -649,6 +649,8 @@ 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;
@@ -661,7 +663,6 @@ 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;
--
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