Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932552AbZIDARS (ORCPT ); Thu, 3 Sep 2009 20:17:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932524AbZIDARR (ORCPT ); Thu, 3 Sep 2009 20:17:17 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:46696 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932505AbZIDARR (ORCPT ); Thu, 3 Sep 2009 20:17:17 -0400 Date: Thu, 3 Sep 2009 17:16:27 -0700 From: Andrew Morton To: Ingo Molnar Cc: arjan@infradead.org, linux-kernel@vger.kernel.org, isdn@linux-pingi.de, isdn4linux@listserv.isdn4linux.de, tj@elte.hu, "David S. Miller" Subject: Re: [PATCH, v3] isdn: Fix stack corruption in isdnloop_init() Message-Id: <20090903171627.2a7e62b8.akpm@linux-foundation.org> In-Reply-To: <20090902140201.GA10854@elte.hu> References: <20090902124402.GA5539@elte.hu> <20090902130336.GA16906@elte.hu> <20090902061439.6c60124c@infradead.org> <20090902140201.GA10854@elte.hu> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3558 Lines: 95 On Wed, 2 Sep 2009 16:02:01 +0200 Ingo Molnar wrote: > From: Ingo Molnar > Date: Tue, 26 May 2009 21:18:22 +0200 > Subject: [PATCH] isdn: Fix stack corruption in isdnloop_init() > > -tip testing found this stack corruption and bootup crash > in the ISDN subsystem, reported by stackprotector: I added this to my little pile of things to send to Linus tomorrow. From: Ingo Molnar -tip testing found this stack corruption and bootup crash in the ISDN subsystem, reported by stackprotector: [ 25.656688] calling isdn_init+0x0/0x2c2 @ 1 [ 25.660388] ISDN subsystem Rev: 1.1.2.3/1.1.2.3/1.1.2.2/1.1.2.3/1.1.2.2/1.1.2.2 [ 25.668179] initcall isdn_init+0x0/0x2c2 returned 0 after 6510 usecs [ 25.670005] calling isdn_bsdcomp_init+0x0/0x45 @ 1 [ 25.673336] PPP BSD Compression module registered [ 25.676674] initcall isdn_bsdcomp_init+0x0/0x45 returned 0 after 3255 usecs [ 25.680005] calling isdnloop_init+0x0/0x88 @ 1 [ 25.683337] isdnloop-ISDN-driver Rev 1.11.6.7 [ 25.686705] isdnloop: (loop0) virtual card added [ 25.690004] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: c1de2d8b [ 25.690006] [ 25.693338] Pid: 1, comm: swapper Not tainted 2.6.31-rc8-tip-01250-geed031c-dirty #9565 [ 25.696672] Call Trace: [ 25.700008] [] ? printk+0x1d/0x30 [ 25.703339] [] panic+0x50/0xed [ 25.706677] [] __stack_chk_fail+0x1e/0x42 [ 25.710005] [] ? isdnloop_init+0x83/0x88 [ 25.713338] [] isdnloop_init+0x83/0x88 [ 25.716674] [] _stext+0x56/0x15a [ 25.720007] [] kernel_init+0x8f/0xf1 [ 25.723338] [] ? kernel_init+0x0/0xf1 [ 25.726675] [] kernel_thread_helper+0x7/0x58 [ 25.730005] Rebooting in 1 seconds..Press any key to enter the menu The bug is that the temporary array: char rev[10]; Is sized one byte too small to store strings based on the 'revision' string. This is a truly ancient bug: it has been introduced in the v2.4.2.1 kernel, ~8.5 years ago, which extended the length of 'revision' by 1 byte. Instead of using a fixed size temporary array, size it based on the 'revision' string. Signed-off-by: Ingo Molnar Cc: Arjan van de Ven Cc: Karsten Keil Cc: Tejun Heo Cc: "David S. Miller" Cc: Signed-off-by: Andrew Morton --- drivers/isdn/isdnloop/isdnloop.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN drivers/isdn/isdnloop/isdnloop.c~isdn-fix-stack-corruption-in-isdnloop_init drivers/isdn/isdnloop/isdnloop.c --- a/drivers/isdn/isdnloop/isdnloop.c~isdn-fix-stack-corruption-in-isdnloop_init +++ a/drivers/isdn/isdnloop/isdnloop.c @@ -15,7 +15,7 @@ #include #include "isdnloop.h" -static char *revision = "$Revision: 1.11.6.7 $"; +static char revision[] = "$Revision: 1.11.6.7 $"; static char *isdnloop_id = "loop0"; MODULE_DESCRIPTION("ISDN4Linux: Pseudo Driver that simulates an ISDN card"); @@ -1494,7 +1494,7 @@ static int __init isdnloop_init(void) { char *p; - char rev[10]; + char rev[sizeof(revision)]; if ((p = strchr(revision, ':'))) { strcpy(rev, p + 1); _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/