From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:47749 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbeB1BJH (ORCPT ); Tue, 27 Feb 2018 20:09:07 -0500 Date: Wed, 28 Feb 2018 01:09:05 +0000 From: "Luis R. Rodriguez" To: Danilo Krummrich Cc: mcgrof@kernel.org, keescook@chromium.org, linux-kernel@vger.kernel.org, Eric Biederman , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v2 1/2] fs/sysctl: fix potential page fault while unregistering sysctl table Message-ID: <20180228010905.GB14069@wotan.suse.de> References: <20180227233156.29826-1-danilokrummrich@dk-develop.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180227233156.29826-1-danilokrummrich@dk-develop.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Feb 28, 2018 at 12:31:55AM +0100, Danilo Krummrich wrote: > proc_sys_link_fill_cache() does not take currently unregistering > sysctl tables into account, which might result into a page fault in > sysctl_follow_link() - add a check to fix it. > > Signed-off-by: Danilo Krummrich > --- > v2: removed empty line between between sysctl_head_grab and IS_ERR Please add a respective tag: Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") And mention this has been present since v3.4. May be worth sending to stable as well, so peg stable as well. Luis > --- > fs/proc/proc_sysctl.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c > index c5cbbdff3c3d..82ac5f682b73 100644 > --- a/fs/proc/proc_sysctl.c > +++ b/fs/proc/proc_sysctl.c > @@ -707,7 +707,10 @@ static bool proc_sys_link_fill_cache(struct file *file, > struct ctl_table *table) > { > bool ret = true; > + > head = sysctl_head_grab(head); > + if (IS_ERR(head)) > + return false; > > if (S_ISLNK(table->mode)) { > /* It is not an error if we can not follow the link ignore it */ > -- > 2.14.1 > > -- Luis Rodriguez, SUSE LINUX GmbH Maxfeldstrasse 5; D-90409 Nuernberg