From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D99CC432C3 for ; Wed, 20 Nov 2019 15:47:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B99F20709 for ; Wed, 20 Nov 2019 15:47:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732644AbfKTPrG (ORCPT ); Wed, 20 Nov 2019 10:47:06 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52544 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729566AbfKTPkP (ORCPT ); Wed, 20 Nov 2019 10:40:15 -0500 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iXS5T-0004a7-Nu; Wed, 20 Nov 2019 15:40:11 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1iXS5T-0004GY-1v; Wed, 20 Nov 2019 15:40:11 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Jia-Ju Bai" , "Jiri Pirko" , "David S. Miller" Date: Wed, 20 Nov 2019 15:37:24 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 14/83] net: sched: Fix a possible null-pointer dereference in dequeue_func() In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jia-Ju Bai commit 051c7b39be4a91f6b7d8c4548444e4b850f1f56c upstream. In dequeue_func(), there is an if statement on line 74 to check whether skb is NULL: if (skb) When skb is NULL, it is used on line 77: prefetch(&skb->end); Thus, a possible null-pointer dereference may occur. To fix this bug, skb->end is used when skb is not NULL. This bug is found by a static analysis tool STCheck written by us. Fixes: 76e3cc126bb2 ("codel: Controlled Delay AQM") Signed-off-by: Jia-Ju Bai Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- --- a/net/sched/sch_codel.c +++ b/net/sched/sch_codel.c @@ -68,7 +68,8 @@ static struct sk_buff *dequeue(struct co { struct sk_buff *skb = __skb_dequeue(&sch->q); - prefetch(&skb->end); /* we'll need skb_shinfo() */ + if (skb) + prefetch(&skb->end); /* we'll need skb_shinfo() */ return skb; }