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 70C896A8D2; Tue, 17 Feb 2026 20:41:21 +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=1771360881; cv=none; b=eVRXzwLZtx3eMqOkRNADroljhKPQqprbK4WU5ykUJkmvxB9+1QzXiZP6KipJAAOhjtxq4zX1iH3AkKxhZ+xgKIdO3D8/2BmOMC/nLWflML5SAYkolxP4lJhoPa2+TnCDuqkOFtbfJiVRLhKmfHXzUhn5F1KV9vLmVT79ZRRbUAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771360881; c=relaxed/simple; bh=+01dTYHepQh1aYaeBzbuHiCiFDIfRHTVovEXwgadCNw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qjZ4nYCD3q9U9TkwBJ4LYM+7BZ0+8/IN47b+Cpazgkm87a1c8TADlEgt6JzPW6zpIsBpZJAvWyi9PJyvDqCACIQKLbltjP98lPFiIgFIYlhnqBxMOD+QKJqi0oRc3tr8488QCD1ieLb/azdDQdWSome32vNzo9pv00naCAKrXkQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QN06LlOC; 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="QN06LlOC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D627C19425; Tue, 17 Feb 2026 20:41:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771360881; bh=+01dTYHepQh1aYaeBzbuHiCiFDIfRHTVovEXwgadCNw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QN06LlOCKqCBciQofcF0WSQoJAjCsQu4rxHHUoWiBBH7joLYthrtjZozqXbth1UfA /GrLyHtUsGWnTqdov2i4Ul2OZ4nuYJ/nmxnhNlRnzFTnSzJwHCjXVhKtnCvlV9Pqu+ FEbS+dzvw1l6M2k5+KYcfg9GwsphpviZkXnnTwkc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+9c4e33e12283d9437c25@syzkaller.appspotmail.com, Deepanshu Kartikey , Christian Brauner , Sasha Levin Subject: [PATCH 6.6 11/39] romfs: check sb_set_blocksize() return value Date: Tue, 17 Feb 2026 21:30:33 +0100 Message-ID: <20260217200004.660356555@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260217200004.221651386@linuxfoundation.org> References: <20260217200004.221651386@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Deepanshu Kartikey [ Upstream commit ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0 ] romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). Later, when sb_bread() attempts I/O with this oversized block size, it triggers a kernel BUG in folio_set_bh(): kernel BUG at fs/buffer.c:1582! BUG_ON(size > PAGE_SIZE); Fix by checking the return value of sb_set_blocksize() and failing the mount with -EINVAL if it returns 0. Reported-by: syzbot+9c4e33e12283d9437c25@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9c4e33e12283d9437c25 Signed-off-by: Deepanshu Kartikey Link: https://patch.msgid.link/20260113084037.1167887-1-kartikey406@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/romfs/super.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/romfs/super.c b/fs/romfs/super.c index b1bdfbc211c3c..82975173dcb04 100644 --- a/fs/romfs/super.c +++ b/fs/romfs/super.c @@ -467,7 +467,10 @@ static int romfs_fill_super(struct super_block *sb, struct fs_context *fc) #ifdef CONFIG_BLOCK if (!sb->s_mtd) { - sb_set_blocksize(sb, ROMBSIZE); + if (!sb_set_blocksize(sb, ROMBSIZE)) { + errorf(fc, "romfs: unable to set blocksize\n"); + return -EINVAL; + } } else { sb->s_blocksize = ROMBSIZE; sb->s_blocksize_bits = blksize_bits(ROMBSIZE); -- 2.51.0