Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752714AbZIBOCY (ORCPT ); Wed, 2 Sep 2009 10:02:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752414AbZIBOCW (ORCPT ); Wed, 2 Sep 2009 10:02:22 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:52374 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707AbZIBOCU (ORCPT ); Wed, 2 Sep 2009 10:02:20 -0400 Date: Wed, 2 Sep 2009 16:02:01 +0200 From: Ingo Molnar To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org, Karsten Keil , isdn4linux@listserv.isdn4linux.de, Andrew Morton , tj@elte.hu Subject: [PATCH, v3] isdn: Fix stack corruption in isdnloop_init() Message-ID: <20090902140201.GA10854@elte.hu> References: <20090902124402.GA5539@elte.hu> <20090902130336.GA16906@elte.hu> <20090902061439.6c60124c@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090902061439.6c60124c@infradead.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3418 Lines: 95 * Arjan van de Ven wrote: > > - char rev[10]; > > + char rev[strlen(revision)+1]; > > > > if ((p = strchr(revision, ':'))) { > > strcpy(rev, p + 1); > > now it;s a runtime variable sized array. > NotNice(tm) ah, indeed - i thought GCC would figure out its constness but it doesnt. v3 should fix this: --------------> >From aa9aff8c2633cf24ad6465d8bf5aa93aa5d91f83 Mon Sep 17 00:00:00 2001 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: [ 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. Cc: Signed-off-by: Ingo Molnar --- drivers/isdn/isdnloop/isdnloop.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c index a335c85..ea07fdd 100644 --- a/drivers/isdn/isdnloop/isdnloop.c +++ b/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/