From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0A40145FE2 for ; Wed, 17 Apr 2024 15:29:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713367798; cv=none; b=tDul6D8dSAzfnN0zj+y9rGvW+evuH+QjsZeHTiQmNhLftJmE0G+aayYmjNUDrQfMopgm5OKpYUrix8D0KAyVUIlWKYHqQr7eypAmxopZSxVFYPSU7CX8j79p6py60E5yI9vj78lbRJZ0wJUlfMKduprFLe/O0SZJBed0jrfstro= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713367798; c=relaxed/simple; bh=2iI96QrTRQ5jyvNs1Lv99V5eEk8SGHk02aKLXCaXwMw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tLjoV1Yl35umBmq41ngDCno1EC3SKlO/9w7QEjhjh6z8V4jLrDkIzcUwrAwwCgj/C44Sskm5fxtHxYIOWO9BitbdSxRGSG1uE26lbIwQXHqUDgnjTFn5EzKTxkdcF5kCgqHnE19Xh3HlvBhDktRU80P+nblHVXWWJu/zeyrFutQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=En+WNy9z; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="En+WNy9z" Received: from cwcc.thunk.org (pool-173-48-113-2.bstnma.fios.verizon.net [173.48.113.2]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 43HFTfQ7015111 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 17 Apr 2024 11:29:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1713367784; bh=bM970VzfEpyjYp5p95QWPLHvSVRRx7peqRZSOKjgA7g=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=En+WNy9zl1Xwaq3WsBsFMsIvn7BVaWDlTn3RaDX6s9Lfa99/Dumgnm/sei778rv1U 3tPZy2HlbKbOfsdnsWq/SfN4jN+6o+NOHvDavLUxLhZ5EOQ74WSFcUhL6H9yYzjCod YRY2A41SEhlSl+/23kMq+q3VWW8TigB4/U7xYLbMo/iEFHwdgpaD23O75IoZMyAuA2 f1dS76aMDUO6BHh6+ioPRL8uRkIgnzk3VTCVO2Bl2CRGIVZzkMY22niQM+Vv0q7nzc uH3mY/RTvxrteGnuUbVMYyrAoN05Y0HkKVpshxv4R1FeJWBdc6fWbClseolo+0Tzq0 1G541e9pfWkzA== Received: by cwcc.thunk.org (Postfix, from userid 15806) id BA4B115C0CBA; Wed, 17 Apr 2024 11:29:41 -0400 (EDT) Date: Wed, 17 Apr 2024 11:29:41 -0400 From: "Theodore Ts'o" To: Jan Kara Cc: Greg Kroah-Hartman , cve@kernel.org, linux-kernel@vger.kernel.org, linux-cve-announce@vger.kernel.org Subject: Re: CVE-2024-26774: ext4: avoid dividing by 0 in mb_update_avg_fragment_size() when block bitmap corrupt Message-ID: <20240417152941.GD2277619@mit.edu> References: <2024040308-CVE-2024-26774-52d9@gregkh> <20240417114324.c77wuw5hvjbm6ok5@quack3> <2024041711-chapter-uninstall-b1d3@gregkh> <20240417145446.uh2rqcbxlebnkbfm@quack3> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240417145446.uh2rqcbxlebnkbfm@quack3> On Wed, Apr 17, 2024 at 04:54:46PM +0200, Jan Kara wrote: > So if we should honestly state the situation (and filesystem folks are > trying to get this message across for a few years already), we should issue > a CVE for "mounting untrusted fs image can crash your kernel or install > rootkit to your system". And yes, I know most distros will happily mount > whatever is plugged into the USB port because that is what users expect and > it is convenient. So if anybody wants a practical solution to this security > problem, I'd suggest working on FUSE drivers for filesystems you care about > and make distros use that when mounting removable media... That is actually > pretty secure and robust solution if you don't care about performance > *that* much. I will note that the insistence of enabling the automounter is apparently the fault of some Red Hat product manager. Alas, our requests to "cut that out" have been ignored. I'll also note that Darrick and I have included udev rules in xfsprogs and e2fsprogs to disable the automounter for ext4 and xfs file systems. I believe the xfsprogs udev rules have already been released, and the ext4 udev rules in e2fsprogs will be released in the next upstream release. It will be interesting to see how many distributions explicitly decide to override our udev rules.... If they do, hopefully the security liability will attach to those distributions, and they will get everything that they deserve. Humming "Flexing like a godd*mn acrobat ; Karma and I vibe like that", - Ted