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 60E768248C for ; Mon, 1 Sep 2025 20:00:45 +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=1756756845; cv=none; b=LML6Gu9ZqP68h+jL6NFfWn5duGJWnw3+nD5GTOPOlrsSaQOPpWKA5NfHGFCliLCzYArOwM8+4aMRSMdLFCmr0YyV63vawwOuS8im4P1pdHj0waoyRvLZ+WfaQXWijNtuNRRPKLqIB5pRwcwD5PKh2b6zHqztxwD8GgN2MNqcITY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756756845; c=relaxed/simple; bh=jTgLGBYnp83yQZTNoCJCr1j3OzKhYuamorr35DI7XFQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Fxol3+THvNb2ksH9KUN2HyNXG36WgDUAmT6B0qr5RjzusrbGfoi6ye5XwYXDmAJGsiv67FoTdGpD5l2NZ6G5urXn3ivWPAa88i0zatgraZ3Y+aHK0AS+5ZhKNCa1UK8xgtmSLiyDy2hycH8fCjiRS0FrdRS4K9TZMizMsqxhC/k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VUbTMXYq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VUbTMXYq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FD5DC4CEF0; Mon, 1 Sep 2025 20:00:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756756844; bh=jTgLGBYnp83yQZTNoCJCr1j3OzKhYuamorr35DI7XFQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VUbTMXYq86qaWeGD3zUZcpnFkpgzZ35awzMlybWzMAwaXTRotwXLbRJUP/uY8utS9 H1+QUV0IPRKUjMvKdPL6dtSYGIiDZOyyo/2RwhOdd/uMGvXN+rG52Bc43awuv2HbPg sXHiIY2ABjqB7fdDEQWlgpMBxYpxHpyVu5A4tvn8= Date: Mon, 1 Sep 2025 22:00:41 +0200 From: Greg Kroah-Hartman To: Norbert Manthey Cc: stable@vger.kernel.org, Amir Goldstein , syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com, Dmitry Safonov , Christian Brauner , =?utf-8?B?w5ZtZXIgRXJkaW7DpyBZYcSfbXVybHU=?= Subject: Re: [PATCH 6.1.y 1/1] fs: relax assertions on failure to encode file handles Message-ID: <2025090116-repent-living-b7de@gregkh> References: <2025011112-racing-handbrake-a317@gregkh> <20250901153559.14799-1-nmanthey@amazon.de> <20250901153559.14799-2-nmanthey@amazon.de> <2025090114-bodacious-daffodil-2f2e@gregkh> Precedence: bulk X-Mailing-List: stable@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: <2025090114-bodacious-daffodil-2f2e@gregkh> On Mon, Sep 01, 2025 at 09:54:03PM +0200, Greg Kroah-Hartman wrote: > On Mon, Sep 01, 2025 at 03:35:59PM +0000, Norbert Manthey wrote: > > From: Amir Goldstein > > > > commit 974e3fe0ac61de85015bbe5a4990cf4127b304b2 upstream. > > > > Encoding file handles is usually performed by a filesystem >encode_fh() > > method that may fail for various reasons. > > > > The legacy users of exportfs_encode_fh(), namely, nfsd and > > name_to_handle_at(2) syscall are ready to cope with the possibility > > of failure to encode a file handle. > > > > There are a few other users of exportfs_encode_{fh,fid}() that > > currently have a WARN_ON() assertion when ->encode_fh() fails. > > Relax those assertions because they are wrong. > > > > The second linked bug report states commit 16aac5ad1fa9 ("ovl: support > > encoding non-decodable file handles") in v6.6 as the regressing commit, > > but this is not accurate. > > > > The aforementioned commit only increases the chances of the assertion > > and allows triggering the assertion with the reproducer using overlayfs, > > inotify and drop_caches. > > > > Triggering this assertion was always possible with other filesystems and > > other reasons of ->encode_fh() failures and more particularly, it was > > also possible with the exact same reproducer using overlayfs that is > > mounted with options index=on,nfs_export=on also on kernels < v6.6. > > Therefore, I am not listing the aforementioned commit as a Fixes commit. > > > > Backport hint: this patch will have a trivial conflict applying to > > v6.6.y, and other trivial conflicts applying to stable kernels < v6.6. > > > > Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com > > Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com > > Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@google.com/ > > Reported-by: Dmitry Safonov > > Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F+Juqy_o6oP8uw@mail.gmail.com/ > > Cc: stable@vger.kernel.org > > Signed-off-by: Amir Goldstein > > Link: https://lore.kernel.org/r/20241219115301.465396-1-amir73il@gmail.com > > Signed-off-by: Christian Brauner > > Signed-off-by: Amir Goldstein > > Signed-off-by: Greg Kroah-Hartman > > I never signed off on the original commit, so why was this added? > > > > > (fuzzy picked from commit f47c834a9131ae64bee3c462f4e610c67b0a000f) > > Applied with LLM-adjusted hunks for 1 functions from us.amazon.nova > > - Changed the function call from `exportfs_encode_fid` to `exportfs_encode_inode_fh` to match the destination code. Wait, that was just fuzz matching, the real body didn't even change. > > - Removed the warning message as per the patch. I do not understand this change, what exactly was this? > Please put this in the proper place, and in the proper format, if you > want to add "notes" to the backport. > > But really, it took a LLM to determine an abi change? That feels like > total overkill as you then had to actually manually check it as well. > But hey, it's your cpu cycles to burn, not mine... Again, total overkill, 1 minute doing a simple git merge resolution would have done the same thing, right? confused as to why this took a whole new tool? We have good merge resolution tools for git these days, what's wrong with using one of the many ones out there? thanks, greg k-h