From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:52926 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751565AbeDAKD7 (ORCPT ); Sun, 1 Apr 2018 06:03:59 -0400 Subject: Re: [PATCH] Btrfs: fix NULL pointer dereference in log_dir_items To: Liu Bo , linux-btrfs@vger.kernel.org References: <1522447918-19147-3-git-send-email-bo.liu@linux.alibaba.com> From: Nikolay Borisov Message-ID: Date: Sun, 1 Apr 2018 13:03:56 +0300 MIME-Version: 1.0 In-Reply-To: <1522447918-19147-3-git-send-email-bo.liu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 31.03.2018 01:11, Liu Bo wrote: > 0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is > returned, path->nodes[0] could be NULL, log_dir_items lacks such a > check for <0 and we may run into a null pointer dereference panic. > > Signed-off-by: Liu Bo Reviewed-by: Nikolay Borisov This bug has been present ever since 2.6.29 (e02119d5a7b4 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")) so this needs a stable tag. > --- > fs/btrfs/tree-log.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c > index 4344577..4ee9431 100644 > --- a/fs/btrfs/tree-log.c > +++ b/fs/btrfs/tree-log.c > @@ -3518,8 +3518,11 @@ static noinline int log_dir_items(struct btrfs_trans_handle *trans, > * from this directory and from this transaction > */ > ret = btrfs_next_leaf(root, path); > - if (ret == 1) { > - last_offset = (u64)-1; > + if (ret) { > + if (ret == 1) > + last_offset = (u64)-1; > + else > + err = ret; > goto done; > } > btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]); >