From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756924AbeDBTJR (ORCPT ); Mon, 2 Apr 2018 15:09:17 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52510 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756743AbeDBTJO (ORCPT ); Mon, 2 Apr 2018 15:09:14 -0400 Date: Mon, 2 Apr 2018 12:09:03 -0700 From: Ram Pai To: Takashi Iwai Cc: Bjorn Helgaas , linux-kernel@vger.kernel.org, Michael Henders Subject: Re: [PATCH] resource: Fix integer overflow at reallocation Reply-To: Ram Pai References: <20180402071616.27177-1-tiwai@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180402071616.27177-1-tiwai@suse.de> User-Agent: Mutt/1.5.20 (2009-12-10) X-TM-AS-GCONF: 00 x-cbid: 18040219-0008-0000-0000-000004E5D717 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18040219-0009-0000-0000-00001E78DE5A Message-Id: <20180402190903.GH5743@ram.oc3035372033.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-04-02_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804020208 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote: > We've got a bug report indicating a kernel panic at booting on an > x86-32 system, and it turned out to be the invalid resource assigned > after reallocation. __find_resource() first aligns the resource start > address and resets the end address with start+size-1 accordingly, then > checks whether it's contained. Here the end address may overflow the > integer, although resource_contains() still returns true because the > function validates only start and end address. So this ends up with > returning an invalid resource (start > end). > > There was already an attempt to cover such a problem in the commit > 47ea91b4052d ("Resource: fix wrong resource window calculation"), but > this case is an overseen one. > > This patch adds the validity check of the newly calculated resource > for avoiding the integer overflow problem. Should we move this check "alloc.start <= alloc.end" into resource_contains()? Doing so will catch all uses of such erroneous (overflowing) resources. RP > > Bugzilla: https://urldefense.proofpoint.com/v2/url?u=http-3A__bugzilla.opensuse.org_show-5Fbug.cgi-3Fid-3D1086739&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=FoiwlR-LTJ9_EBQsLYSCqXuWrGhU1lXycdvhbaK7wOk&s=clxOtFUIAMlPNwQJZTaKnmIta9pMtJ8XprmwVd-ylvo&e= > Fixes: 23c570a67448 ("resource: ability to resize an allocated resource") > Reported-and-tested-by: Michael Henders > Cc: > Signed-off-by: Takashi Iwai > --- > > Bjorn, I send this to you since the bug hits during PCI init, although > the culprit is in generic resource management. > > kernel/resource.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/resource.c b/kernel/resource.c > index e270b5048988..2af6c03858b9 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old, > alloc.start = constraint->alignf(constraint->alignf_data, &avail, > size, constraint->align); > alloc.end = alloc.start + size - 1; > - if (resource_contains(&avail, &alloc)) { > + if (alloc.start <= alloc.end && > + resource_contains(&avail, &alloc)) { > new->start = alloc.start; > new->end = alloc.end; > return 0; > -- > 2.16.2 -- Ram Pai