From patchwork Tue Feb 27 23:31:55 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 10246353 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9A75260362 for ; Tue, 27 Feb 2018 23:32:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 90B9D287FD for ; Tue, 27 Feb 2018 23:32:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8558828B06; Tue, 27 Feb 2018 23:32:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1FAD2287FD for ; Tue, 27 Feb 2018 23:32:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751706AbeB0XcB (ORCPT ); Tue, 27 Feb 2018 18:32:01 -0500 Received: from hs01.dk-develop.de ([213.136.71.231]:35134 "EHLO hs01.dk-develop.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbeB0XcB (ORCPT ); Tue, 27 Feb 2018 18:32:01 -0500 Received: from danilo-linux.fritz.box (ipbcc13fda.dynamic.kabel-deutschland.de [188.193.63.218]) by hs01.dk-develop.de (Postfix) with ESMTPSA id 9AD2E1320D2B; Wed, 28 Feb 2018 00:32:04 +0100 (CET) From: Danilo Krummrich To: mcgrof@kernel.org, keescook@chromium.org Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Danilo Krummrich Subject: [PATCH v2 1/2] fs/sysctl: fix potential page fault while unregistering sysctl table Date: Wed, 28 Feb 2018 00:31:55 +0100 Message-Id: <20180227233156.29826-1-danilokrummrich@dk-develop.de> X-Mailer: git-send-email 2.14.1 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: Kees Cook --- v2: removed empty line between between sysctl_head_grab and IS_ERR --- 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 */