From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031667AbeE1KVY (ORCPT ); Mon, 28 May 2018 06:21:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:40776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1033294AbeE1KVN (ORCPT ); Mon, 28 May 2018 06:21:13 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Danilo Krummrich , Kees Cook , Andrew Morton , "Luis R . Rodriguez" , "Eric W. Biederman" , Alexey Dobriyan , Linus Torvalds , Sasha Levin Subject: [PATCH 4.4 160/268] fs/proc/proc_sysctl.c: fix potential page fault while unregistering sysctl table Date: Mon, 28 May 2018 12:02:14 +0200 Message-Id: <20180528100220.598044371@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100202.045206534@linuxfoundation.org> References: <20180528100202.045206534@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Danilo Krummrich [ Upstream commit a0b0d1c345d0317efe594df268feb5ccc99f651e ] 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. This bug has been present since v3.4. Link: http://lkml.kernel.org/r/20180228013506.4915-1-danilokrummrich@dk-develop.de Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") Signed-off-by: Danilo Krummrich Acked-by: Kees Cook Reviewed-by: Andrew Morton Cc: "Luis R . Rodriguez" Cc: "Eric W. Biederman" Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/proc/proc_sysctl.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -654,7 +654,10 @@ static bool proc_sys_link_fill_cache(str 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 */