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 CD3DEC4332F for ; Wed, 23 Nov 2022 08:57:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236770AbiKWI5V (ORCPT ); Wed, 23 Nov 2022 03:57:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236853AbiKWI5B (ORCPT ); Wed, 23 Nov 2022 03:57:01 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE463FFA90 for ; Wed, 23 Nov 2022 00:57:00 -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 sin.source.kernel.org (Postfix) with ESMTPS id A58DECE20F0 for ; Wed, 23 Nov 2022 08:56:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60EFCC433C1; Wed, 23 Nov 2022 08:56:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669193816; bh=Davon7GOtFq0RxRtwQqzxLJYBvRmaKjU7qktvhm7MQU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e0eXHqCrNDp+j5n6YFStrNBXdH64Cx+0SJf0Cpelx1fYe4YkEp3vVwfjmOYtZWhGS wW1XF6avJZ8iOnK33K6niZ/GE0MlxJau1MOBOYcOsv1k0NLW+EPGL0SgSU/QRids7T 7j+XfBmyc92YzgF9VIdCs5ucqxGfeTBMEHwpm8mI= 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 4.9 70/76] gfs2: Check sb_bsize_shift after reading superblock Date: Wed, 23 Nov 2022 09:51:09 +0100 Message-Id: <20221123084549.045986759@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084546.742331901@linuxfoundation.org> References: <20221123084546.742331901@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 @@ -171,7 +171,10 @@ 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; }