Return-Path: Received: from mx143.netapp.com ([216.240.21.24]:47370 "EHLO mx143.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753280AbcGSPVP (ORCPT ); Tue, 19 Jul 2016 11:21:15 -0400 From: Anna Schumaker Subject: Re: [PATCH] Fix NULL pointer dereference in bl_free_device(). To: Artem Savkov , References: <1468927851-2186-1-git-send-email-asavkov@redhat.com> CC: , , Message-ID: Date: Tue, 19 Jul 2016 11:21:08 -0400 MIME-Version: 1.0 In-Reply-To: <1468927851-2186-1-git-send-email-asavkov@redhat.com> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi Artem, On 07/19/2016 07:30 AM, Artem Savkov wrote: > When bl_parse_deviceid() fails in bl_alloc_deviceid_node() on > blkdev_get_by_*() step we get an pnfs_block_dev struct that is > uninitialized except for bdev field which is set to whatever error > blkdev_get_by_*() returns. bl_free_device() then tries to call > blkdev_put() if bdev is not 0 resulting in a wrong pointer dereference. > > Fixing this by making sure bdev is not an error code in bl_free_device(). > > Signed-off-by: Artem Savkov > --- > fs/nfs/blocklayout/dev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c > index 118252f..7db3af0 100644 > --- a/fs/nfs/blocklayout/dev.c > +++ b/fs/nfs/blocklayout/dev.c > @@ -33,7 +33,7 @@ bl_free_device(struct pnfs_block_dev *dev) > pr_err("failed to unregister PR key.\n"); > } > > - if (dev->bdev) > + if (dev->bdev && !IS_ERR(dev->bdev)) This looks pretty straightforward, but can you use IS_ERR_OR_NULL() instead? It accomplishes the same check with slightly cleaner code :) Thanks, Anna > blkdev_put(dev->bdev, FMODE_READ | FMODE_WRITE); > } > } >