xen/blkback: Check device permissions before allowing OP_DISCARD
We need to make sure that the device is not RO or that
the request is not past the number of sectors we want to
issue the DISCARD operation for.
This fixes CVE-2013-2140.
Cc: stable@vger.kernel.org
Acked-by: Jan Beulich <JBeulich@suse.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
[v1: Made it pr_warn instead of pr_debug]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index e79ab45..4119bcd 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -876,7 +876,18 @@
int status = BLKIF_RSP_OKAY;
struct block_device *bdev = blkif->vbd.bdev;
unsigned long secure;
+ struct phys_req preq;
+ preq.sector_number = req->u.discard.sector_number;
+ preq.nr_sects = req->u.discard.nr_sectors;
+
+ err = xen_vbd_translate(&preq, blkif, WRITE);
+ if (err) {
+ pr_warn(DRV_PFX "access denied: DISCARD [%llu->%llu] on dev=%04x\n",
+ preq.sector_number,
+ preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
+ goto fail_response;
+ }
blkif->st_ds_req++;
xen_blkif_get(blkif);
@@ -887,7 +898,7 @@
err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
req->u.discard.nr_sectors,
GFP_KERNEL, secure);
-
+fail_response:
if (err == -EOPNOTSUPP) {
pr_debug(DRV_PFX "discard op failed, not supported\n");
status = BLKIF_RSP_EOPNOTSUPP;