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xen/blkback: Check device permissions before allowing OP_DISCARD

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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>
This commit is contained in:
Konrad Rzeszutek Wilk 2013-01-16 11:33:52 -05:00
parent 7c4d7d710f
commit 604c499cbb
1 changed files with 12 additions and 1 deletions
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13
drivers/block/xen-blkback/blkback.c
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@ -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;