From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753572AbcGSPVQ (ORCPT ); Tue, 19 Jul 2016 11:21:16 -0400 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 S1752534AbcGSPVN (ORCPT ); Tue, 19 Jul 2016 11:21:13 -0400 X-IronPort-AV: E=Sophos;i="5.28,390,1464678000"; d="scan'208";a="128299792" 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: <6cf8c0f8-37d9-cf60-8607-20b933d248ae@Netapp.com> Date: Tue, 19 Jul 2016 09:57:39 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1468927851-2186-1-git-send-email-asavkov@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); > } > } >