From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.218.44 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794658799; b=VWy/CcAqOtGTtNajuySqQ73viZ+3/dj24oZC9OKEodrXkZYWpBbF3vgWGhtXAAWdvm6C UG/JsuXmoy0NmklK5IzAXFhw1KlxE/Vndpycfo+zdElYtUGGGSxMXx0Gs/PmizPl8U8n9 Y4HabxbmjGzcGYJkwcYErttCpyCyqRTUqGDvc52J4eyovY4lX8xjCuZxhYIMeBWAJxigE Yo7d4w9YAe6kXKrOesEmxhEraRDUwdI4z6ciYJNLJcL2Mxvf8otCShjlJzXlldc7rqHNd Az0tUT5f39/Gjuf1uikfe5Uw7D1gN5Xz2PzQvhIZNULEeIXiCiZdn+QrFZbN9gkRSMA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794658799; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; bh=nkM3J4QAu8kIsGHpB1EKb0NRF0JxtY2T/gqGpQ/nt0Q=; b=5f1gg/4H3WYdT3v14bBgi0T3FJ5f/f6LiC5EjP98U+Po9ZUnrRFJ06YqUy2ylV0LRuOI LhlIYYhEovBPZpJLPMnhJqsOZKKDFw4uNeOt9acrNQgKkA123jNdFHF+pKO92W+OIfdvl btoBCb1TLxf90rMknR+yH/8YrJTOET/KgdXdSxOvXuuagCkjfOuXyIONj0w/f/u7OlT5i n+WeesPVD6efvDUlGwKPCBCDiWDY0kpHpdIkzu/D3p7cmTkePJQpe4OLKrj9phimBbGKR u206Ye0lzq+UeBylb498aQzln8v2xSi3a1xIjMpfmd7B03fPtmJAQLkHeU3qOlLB3Cw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Zvg2B30u; arc=none smtp.remote-ip=209.85.218.44 Received: from mail-ej1-f44.google.com (mail-ej1-f44.google.com [209.85.218.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3170C606A330 for ; Sat, 14 Nov 2026 12:19:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3170C606A330 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Zvg2B30u Received: by mail-ej1-f44.google.com with SMTP id a640c23a62f3a-c40e30c26a4so402487166b.0 for ; Sat, 14 Nov 2026 04:19:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1794658797; x=1795263597; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=nkM3J4QAu8kIsGHpB1EKb0NRF0JxtY2T/gqGpQ/nt0Q=; b=Zvg2B30uBzOFFo54OpfHCzqSK6TOyxTRmwNZV7t2nfrBwunaCrRH+5tI09/jIosXZS GdYk6iMfyO0nJ3moVzjaSKnXCCWxcV1Ye+R/4YjiwdwGG8ofIv4PWH24MjP/VV4CkNiq nSM7j6UNEdEDdNWpjUjn43q9YL/wt1IFltOrsPhL2VYrn8g/yyR7Uz6PFelA0j1tolIT QTqiv37OCVMy+5oEwlNBsw2cKiejzgZGAC7AZW2QPAu9cR2dMcfIteYf8vq02JyCIN53 /PYiFz/vA+fp7KPo0fCiRfu55fCeLd5qLFIcUMGbAUVH1mkivaDzQTprXnn5n1PDT9pn 6ZTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794658797; x=1795263597; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=nkM3J4QAu8kIsGHpB1EKb0NRF0JxtY2T/gqGpQ/nt0Q=; b=YuHIJ6JhDArAH/GN8B3Haw2yAXIkfcGnOgZHebDgS69mEHtprtntPo7W6d0h5kCorw 7UhGJuGO6c3YMOcaXgNwoDRy7UnfZyFQqPgXGZdbBmRtFd5XiO6FMUzRBRd2Htpkju5o Uj+hEnOikgyiq/V/XgLwVVvaAXBDQNgwrIv/+rFX4JpRqiTrUgX1nvqzKQHR/+5AoZ6A 5qgXzCZ9s/ep74ayh2eiM9MVLpYugvXmHwjyogXanGZ8VF0wJS4fHE8vqfPcAB3UfZ1i s5rw0PVbpKFW6yarcX9fYEY3dkeakRLd5c97NKGqni0ZO4VBoguUoMnNfv6r8gLP5NrR wzGA== X-Forwarded-Encrypted: i=1; AL+hErFvNSekW4Mbx9bnoBVZe8tRPVBMTGIPp4iOgH6a/lda+ClMbh5/CGRTHXGAkRGE1wq1hgVNRNqjUWU=@vger.kernel.org X-Gm-Message-State: APuU4Z9ubkDMhY+Nzo/kzEdZ5GNX1/tbcT7Daxvb6Y2Cyb7lNCfCTmpm G8BZW4w5wCPF4qqqc++6S0vRLvRWQUtfAa4QiIXXErUw88l1EzEQEJe2 X-Gm-Gg: AYBFou0DptP3uuBi1xAZOZOR+dZ0cG8HJPQ4GQXQoiZpyesieVdzId440Bu0cJrNrxE VY4/zJ4QwnfjM2753JyQbU4Rn4DTrRdeaP18KhCmuCDAuoqEex1FQIZtYSHoY7HaU4vbs586fot 7YrHLIIBGMQcm6jE+UNt4hWidt0YfyzqyvtPVn3U4ogRycvOZjEoW4MbbiuROBVqHXUYEeyMzA7 0gBhahUZB6A0zNVoa5O9o7s/czpRKLE76+VafsZJm9t79Ty3WLTUCVt8BPAfl+GNV2Q3zy0/rRL a/DmwwKyn2ioxHooLd42LiMPwqDtDa4BIrQZ/GcUGa1KoLvuIlQz8ECwgMditTcGpC5nmffNaaP sfJqzvqbVLzzbVTmn54MLAEQ4vc2u4uv8ewZIxcs7okO2pizNb9f4pdDggDD5pgns4jYQ5n2sL1 eqrv/CyD3wVL/+5+r+fONfwbpT/bvqJgO/RK2aOw1c9ou672dRBTrjuRHVMMcb+qHmjVnvOwV+z E732yBY+eKVl3rsTbIqSa7MpFQWkXU0KRt2CMNAOfb2w13BJfgJnqFUyc7VHkjgCkulbjw40BEA BJSkJfotvUIMYMaDwAdNIZwGyurh3rPmEuPnycFanVSXJzcobjecPJNHmJH+g3BVz+XLE6lsRc7 KsOHZNACNs8kJ X-Received: by 2002:a17:906:1001:10b0:c41:4512:560d with SMTP id a640c23a62f3a-c5096387b02mr309942166b.16.1794658797424; Sat, 14 Nov 2026 04:19:57 -0800 (PST) Received: from localhost (178-84-201-199.dynamic.upc.nl. [178.84.201.199]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c5095b5ac2asm211518966b.55.2026.11.14.04.19.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 04:19:56 -0800 (PST) Date: Sat, 14 Nov 2026 13:19:56 +0100 From: Amir Goldstein To: Christian Brauner Cc: Jan Kara , Shakeel Butt , Alexander Viro , Jens Axboe , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, Christoph Hellwig , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-unionfs@vger.kernel.org, bpf@vger.kernel.org, linux-nfs@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 10/12] ovl: take freeze protection when storing the uuid Message-ID: References: <20261114-work-fs-frozen_writes-v1-0-f5ae61c898b1@kernel.org> <20261114-work-fs-frozen_writes-v1-10-f5ae61c898b1@kernel.org> X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261114-work-fs-frozen_writes-v1-10-f5ae61c898b1@kernel.org> On Sat, Nov 14, 2026 at 11:47:17AM +0100, Christian Brauner wrote: > ovl_init_uuid_xattr() stores the persistent uuid in an xattr on the > upper root. That happens after ovl_make_workdir() dropped its write > access to the upper mount and before ovl_get_indexdir() takes it > again. So a freeze of the upper filesystem that lands in between lets > the mount modify a frozen filesystem. > > Take write access to the upper mount around the xattr update. > > Fixes: d9544c1b0d9e ("ovl: store persistent uuid/fsid with uuid=on") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Brauner (Amutable) Reviewed-by: Amir Goldstein Thanks, Amir. > --- > fs/overlayfs/util.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c > index 521717209b2e4..67aa7b71e9c83 100644 > --- a/fs/overlayfs/util.c > +++ b/fs/overlayfs/util.c > @@ -829,8 +829,12 @@ bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs, > > /* Try to store persistent uuid */ > set = true; > - res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, uuid.b, > - UUID_SIZE); > + res = mnt_want_write(ovl_upper_mnt(ofs)); > + if (!res) { > + res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, > + uuid.b, UUID_SIZE); > + mnt_drop_write(ovl_upper_mnt(ofs)); > + } > if (res) > goto fail; > > > -- > 2.53.0 >