From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9C22C433FE for ; Wed, 23 Nov 2022 09:19:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237306AbiKWJTR (ORCPT ); Wed, 23 Nov 2022 04:19:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237395AbiKWJSx (ORCPT ); Wed, 23 Nov 2022 04:18:53 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1022618369 for ; Wed, 23 Nov 2022 01:18:37 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B36B9B81EF2 for ; Wed, 23 Nov 2022 09:18:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCC33C433C1; Wed, 23 Nov 2022 09:18:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669195114; bh=bO6VjUpxjWLmvytzvPXq4DiuqihN5bYhuUqtiq6cn7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Wrfe4srAtcqzoU74aVV5OeA5Emee5ca7dh7msi4AgCGTGFgRG9nIcIBeLz1C61rLR QlL6yhPutGirrybq0h6r3arJK0XPMesbovOmGshn+2Xve/zrgFWmtJR8DKx0rGSzZk XWD42RfzUXbZygl+ZMo1rZmhN2vy+XTllfj9NP88= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+dcf33a7aae997956fe06@syzkaller.appspotmail.com, Andrew Price , Andreas Gruenbacher Subject: [PATCH 5.4 150/156] gfs2: Check sb_bsize_shift after reading superblock Date: Wed, 23 Nov 2022 09:51:47 +0100 Message-Id: <20221123084603.263309195@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084557.816085212@linuxfoundation.org> References: <20221123084557.816085212@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andrew Price commit 670f8ce56dd0632dc29a0322e188cc73ce3c6b92 upstream. Fuzzers like to scribble over sb_bsize_shift but in reality it's very unlikely that this field would be corrupted on its own. Nevertheless it should be checked to avoid the possibility of messy mount errors due to bad calculations. It's always a fixed value based on the block size so we can just check that it's the expected value. Tested with: mkfs.gfs2 -O -p lock_nolock /dev/vdb for i in 0 -1 64 65 32 33; do gfs2_edit -p sb field sb_bsize_shift $i /dev/vdb mount /dev/vdb /mnt/test && umount /mnt/test done Before this patch we get a withdraw after [ 76.413681] gfs2: fsid=loop0.0: fatal: invalid metadata block [ 76.413681] bh = 19 (type: exp=5, found=4) [ 76.413681] function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 492 and with UBSAN configured we also get complaints like [ 76.373395] UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19 [ 76.373815] shift exponent 4294967287 is too large for 64-bit type 'long unsigned int' After the patch, these complaints don't appear, mount fails immediately and we get an explanation in dmesg. Reported-by: syzbot+dcf33a7aae997956fe06@syzkaller.appspotmail.com Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Greg Kroah-Hartman --- fs/gfs2/ops_fstype.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/fs/gfs2/ops_fstype.c +++ b/fs/gfs2/ops_fstype.c @@ -180,7 +180,10 @@ static int gfs2_check_sb(struct gfs2_sbd pr_warn("Invalid superblock size\n"); return -EINVAL; } - + if (sb->sb_bsize_shift != ffs(sb->sb_bsize) - 1) { + pr_warn("Invalid block size shift\n"); + return -EINVAL; + } return 0; }