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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 358E9C282DA for ; Sun, 3 Feb 2019 13:54:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2687218D8 for ; Sun, 3 Feb 2019 13:54:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729047AbfBCNy1 (ORCPT ); Sun, 3 Feb 2019 08:54:27 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54424 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728758AbfBCNyU (ORCPT ); Sun, 3 Feb 2019 08:54:20 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqIDz-0003tt-Ic; Sun, 03 Feb 2019 13:54:19 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9r-0007Ot-L8; Sun, 03 Feb 2019 14:50:03 +0100 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 , "Macpaul Lin" , "Greg Kroah-Hartman" , "Daniel Thompson" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 270/305] kgdboc: fix KASAN global-out-of-bounds bug in param_set_kgdboc_var() In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 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 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Macpaul Lin commit dada6a43b0402eba438a17ac86fdc64ac56a4607 upstream. This patch is trying to fix KE issue due to "BUG: KASAN: global-out-of-bounds in param_set_kgdboc_var+0x194/0x198" reported by Syzkaller scan." [26364:syz-executor0][name:report8t]BUG: KASAN: global-out-of-bounds in param_set_kgdboc_var+0x194/0x198 [26364:syz-executor0][name:report&]Read of size 1 at addr ffffff900e44f95f by task syz-executor0/26364 [26364:syz-executor0][name:report&] [26364:syz-executor0]CPU: 7 PID: 26364 Comm: syz-executor0 Tainted: G W 0 [26364:syz-executor0]Call trace: [26364:syz-executor0][] dump_bacIctrace+Ox0/0x470 [26364:syz-executor0][] show_stack+0x20/0x30 [26364:syz-executor0][] dump_stack+Oxd8/0x128 [26364:syz-executor0][] print_address_description +0x80/0x4a8 [26364:syz-executor0][] kasan_report+Ox178/0x390 [26364:syz-executor0][] _asan_report_loadi_noabort+Ox18/0x20 [26364:syz-executor0][] param_set_kgdboc_var+Ox194/0x198 [26364:syz-executor0][] param_attr_store+Ox14c/0x270 [26364:syz-executor0][] module_attr_store+0x60/0x90 [26364:syz-executor0][] sysfs_kl_write+Ox100/0x158 [26364:syz-executor0][] kernfs_fop_write+0x27c/0x3a8 [26364:syz-executor0][] do_loop_readv_writev+0x114/0x1b0 [26364:syz-executor0][] do_readv_writev+0x4f8/0x5e0 [26364:syz-executor0][] vfs_writev+0x7c/Oxb8 [26364:syz-executor0][] SyS_writev+Oxcc/0x208 [26364:syz-executor0][] elO_svc_naked +0x24/0x28 [26364:syz-executor0][name:report&] [26364:syz-executor0][name:report&]The buggy address belongs to the variable: [26364:syz-executor0][name:report&] kgdb_tty_line+Ox3f/0x40 [26364:syz-executor0][name:report&] [26364:syz-executor0][name:report&]Memory state around the buggy address: [26364:syz-executor0] ffffff900e44f800: 00 00 00 00 00 04 fa fa fa fa fa fa 00 fa fa fa [26364:syz-executor0] ffffff900e44f880: fa fa fa fa 00 fa fa fa fa fa fa fa 00 fa fa fa [26364:syz-executor0]> ffffff900e44f900: fa fa fa fa 04 fa fa fa fa fa fa fa 00 00 00 00 [26364:syz-executor0][name:report&] ^ [26364:syz-executor0] ffffff900e44f980: 00 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa [26364:syz-executor0] ffffff900e44fa00: 04 fa fa fa fa fa fa fa 00 fa fa fa fa fa fa fa [26364:syz-executor0][name:report&] [26364:syz-executor0][name:panic&]Disabling lock debugging due to kernel taint [26364:syz-executor0]------------[cut here]------------ After checking the source code, we've found there might be an out-of-bounds access to "config[len - 1]" array when the variable "len" is zero. Signed-off-by: Macpaul Lin Acked-by: Daniel Thompson Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/tty/serial/kgdboc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -252,7 +252,7 @@ static void kgdboc_put_char(u8 chr) static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp) { - int len = strlen(kmessage); + size_t len = strlen(kmessage); if (len >= MAX_CONFIG_LEN) { printk(KERN_ERR "kgdboc: config string too long\n"); @@ -274,7 +274,7 @@ static int param_set_kgdboc_var(const ch strcpy(config, kmessage); /* Chop out \n char as a result of echo */ - if (config[len - 1] == '\n') + if (len && config[len - 1] == '\n') config[len - 1] = '\0'; if (configured == 1)