From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6EE5C21E098; Mon, 7 Apr 2025 10:59:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744023564; cv=none; b=PeAQMp/JW51CT2yDyMyWu/rFdfxuCH4xRQgFBbO54MtTRrzCkcUvLmGWQ9yndQZjOIicPX9Jq8PimzJ/JAH+w5ubf6MHS3E1GPN8pjhQd3YpA71FBzdYlq4YPxYxzq9wGNNackVHC7pbv4vHafn1rUXqlXDhk6Vs/Vdn5kQpPvg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744023564; c=relaxed/simple; bh=zylTLIN0qUpLoPTgkIgrGalrS9zEVqUvpzxrYi2gcVU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=is7qiQFycxTVdNP5P6z3J67ko0KwNADk7p74KdojN5bB/xed9moG3iG/F8rbvJjQbKmUUZzoDrtJSSxfS3CXigGwxJnf6CaIUBcXxjX44mmLLPnQlltlv+kVGrzI7NiBU3ZGWl0RkSyonbbC5KLQHfnz7txErIYamchc22GuGkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XrqLyh0w; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XrqLyh0w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FEA2C4CEDD; Mon, 7 Apr 2025 10:59:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744023563; bh=zylTLIN0qUpLoPTgkIgrGalrS9zEVqUvpzxrYi2gcVU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XrqLyh0wT0ExUkwKa097cUipLfCYdPndBjwXJMAmVk/1TmkR8GnslLCv8dvO5NtNJ O/gx+O+az3b+TCC05Vdx82BjU2pE2y6Rl4qcGv3bVgSmX0jxJtTg7SYKhT/TKbbutb 4AHr4qYTKrYoBg73kIpD8AMREoMihES7MzVGqmiHplpIjB+AUFel53Xlw0zXdWVt42 bfICta+Mq8hntLEtjCM19UKbXzqJpKMBt1CRu4XzftRIexl8UVr6ACIMqWhJ04wzNj gHXSJAl+hmzcAtnTF/BiZ6CNJkJzndjjVMPfXizbI37cDzctnQeJYSieSknJBaEVYz hHTPLTfXk08gg== Date: Mon, 7 Apr 2025 12:59:18 +0200 From: Christian Brauner To: Cengiz Can , Attila Szasz Cc: Greg KH , Salvatore Bonaccorso , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, lvc-patches@linuxtesting.org, dutyrok@altlinux.org, syzbot+5f3a973ed3dfb85a6683@syzkaller.appspotmail.com, stable@vger.kernel.org, Alexander Viro Subject: Re: [PATCH] hfs/hfsplus: fix slab-out-of-bounds in hfs_bnode_read_key Message-ID: <20250407-biegung-furor-e7313ca9d712@brauner> References: <20241019191303.24048-1-kovalev@altlinux.org> <2025032402-jam-immovable-2d57@gregkh> <7qi6est65ekz4kjktvmsbmywpo5n2kla2m3whbvq4dsckdcyst@e646jwjazvqh> <2025032404-important-average-9346@gregkh> 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=utf-8 Content-Disposition: inline In-Reply-To: On Sun, Apr 06, 2025 at 07:07:57PM +0300, Cengiz Can wrote: > On 24-03-25 11:53:51, Greg KH wrote: > > On Mon, Mar 24, 2025 at 09:43:18PM +0300, Cengiz Can wrote: > > > In the meantime, can we get this fix applied? > > > > Please work with the filesystem maintainers to do so. > > Hello Christian, hello Alexander > > Can you help us with this? > > Thanks in advance! Filesystem bugs due to corrupt images are not considered a CVE for any filesystem that is only mountable by CAP_SYS_ADMIN in the initial user namespace. That includes delegated mounting. Now, quoting from [1]: "So, for the record, the Linux kernel in general only allows mounts for those with CAP_SYS_ADMIN, however, it is true that desktop and even server environments allow regular non-privileged users to mount and automount filesystems. In particular, both the latest Ubuntu Desktop and Server versions come with default polkit rules that allow users with an active local session to create loop devices and mount a range of block filesystems commonly found on USB flash drives with udisks2. Inspecting /usr/share/polkit-1/actions/org.freedesktop.UDisks2.policy shows:" So what this saying is: A distribution is shipping tooling that allows unprivileged users to mount arbitrary filesystems including hpfsplus. Or to rephrase this: A distribution is allowing unprivileged users to mount orphaned filesystems. Congratulations on the brave decision to play Russian Roulette with a fully-loaded gun. The VFS doesn't allow mounting arbitrary filesystems by unprivileged users. Every FS_REQUIRES_DEV filesystem requires global CAP_SYS_ADMIN privileged at which point you can also do sudo rm -rf --no-preserve-root / or a million other destructive things. The blogpost is aware that the VFS maintainers don't accept CVEs like this. Yet a CVE was still filed against the upstream kernel. IOW, someone abused the fact that a distro chose to allow mounting arbitrary filesystems including orphaned ones by unprivileged user as an argument to gain a kernel CVE. Revoke that CVE against the upstream kernel. This is a CVE against a distro. There's zero reason for us to hurry with any fix. [1]: https://ssd-disclosure.com/ssd-advisory-linux-kernel-hfsplus-slab-out-of-bounds-write/