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Commit 604c499c authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

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: default avatarJan Beulich <JBeulich@suse.com>
Acked-by: default avatarIan Campbell <Ian.Campbell@citrix.com>
[v1: Made it pr_warn instead of pr_debug]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 7c4d7d71

drivers/block/xen-blkback/blkback.c

+12 −1
Original line number Diff line number Diff line
@@ -876,7 +876,18 @@ static int dispatch_discard_io(struct xen_blkif *blkif, 
	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 @@ static int dispatch_discard_io(struct xen_blkif *blkif, 
	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;