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 85B572139B5 for ; Fri, 9 May 2025 14:17:29 +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=1746800251; cv=none; b=AxttvDDsNQjJouL0Y0OPPeWzcP51nPQ+55m9d8S7MG1cvZqxbitW8JS46hPjVnFJs4ylqxPhVf00b1oCdlDXY0y3wfOXh5w5q/LBbGI2Ml7P4WQKW0xTTGWUodUg/xB+ZgP7tV0MVSVhXBhOCO9fkwXjNK1mgRdjkAUTXRYz/8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746800251; c=relaxed/simple; bh=OtQKOG7VhTI3zdW6+rNp3Aflv3idF1yielCwycvSK7c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sNKcDRQZkIdWJ9lRM0WCa38bHMQHpTXX+zSH2J0ypWflXyL0LZqUavJLg22vyOX+mICwnB22r4/5YcuXfUW+jW7qJZrAKygSwwl4J7Vadb+KslSXEwzG25bEs5XlvpneuivmHosu+rYbtn4tdWWNn5VWl6BgYgK/VDPn8axhcy8= 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; 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 Received: from trampoline.thunk.org (pool-173-48-82-148.bstnma.fios.verizon.net [173.48.82.148]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 549EHFtw028787 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 9 May 2025 10:17:16 -0400 Received: by trampoline.thunk.org (Postfix, from userid 15806) id CFDAE2E00E1; Fri, 09 May 2025 10:17:15 -0400 (EDT) Date: Fri, 9 May 2025 10:17:15 -0400 From: "Theodore Ts'o" To: Attila Szasz Cc: Dmitry Vyukov , Greg KH , cve@kernel.org, linux-cve-announce@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: REJECTED: CVE-2025-0927: heap overflow in the hfs and hfsplus filesystems with manually crafted filesystem Message-ID: <20250509141715.GC92783@mit.edu> References: <2025040820-REJECTED-6695@gregkh> <20250509072033.1335321-1-dvyukov@google.com> <2025050940-marrow-roundish-8b98@gregkh> <2025050924-marmalade-overfill-fc5a@gregkh> <20250509121036.GA92783@mit.edu> <6191c255-84cc-4721-91d1-1884472989f7@gmail.com> 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: <6191c255-84cc-4721-91d1-1884472989f7@gmail.com> On Fri, May 09, 2025 at 03:18:19PM +0200, Attila Szasz wrote: > > Since then, I saw Canonical folks mention that they wanted to > allocate a new one but needed to obfuscate the description so it no > longer sounds like a kernel bug. Sure, it's an automounter bug; or an fsck bug, assuming that their system is running fsck -y on the file system before trying to mount the file system. > Which, incidentally, is not quite true either, it *is* a kernel bug. > > Since then I checked, and 5.4 LTS (any<=5.6) had been vulnerable without > the need to ever mount an untrusted/malformed FS just by systematically > corrupting a vanilla fs's B-trees with normal operations. So if you can come up with a reproducer that *starts* with a valid file system which passes fsck, and then using normal, non-root operations, you can corrupt the file system and then trigger a kernel crash or some vulnerability, then that's a valid security bug in my opinion. I'll certainly treat it that way for ext4. But you need to demonstrate this using a reproducer that doesn't start with a fuzzed file system. In my experience, this rules out 99% of syzbot bugs reported against ext4. But if you can come up with such a reproducer, send the POC to the file system developer, and ask them to address it. If it's against ext4, I'll get on it right away. > There was also a logic issue I wrote about that hasn't been > patched, since hfs_brec_find() can return with -ENOENT, and > hfsplus_create_attr did not treat ENOENT as a problem when > inserting records, resulting in a flow completely missing the > only boundary checks that were present earlier. With the issue > that commit 25efb2f patched upstream and another issue I found, > the condition for the rejection is no longer true. > The image to begin with is not even corrupt. Great, but that's not this CVE. Note that it was entitled "... with manually crafted filesystem" - Ted