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 5E862C32774 for ; Tue, 23 Aug 2022 08:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242827AbiHWITL (ORCPT ); Tue, 23 Aug 2022 04:19:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242376AbiHWIOh (ORCPT ); Tue, 23 Aug 2022 04:14:37 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1F796CF41; Tue, 23 Aug 2022 01:09:50 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id F1E716126A; Tue, 23 Aug 2022 08:09:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5CADC433C1; Tue, 23 Aug 2022 08:09:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661242189; bh=6U83wbLARbMC175D+M8iSXUKvFzWTq2N2fBB1jY3bHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GSI32Wiu1I+I1dfF3UIqeb4vnbH+nYbn+9NZXksouwF2k2HqvxWVmQ/1FDKqmIWWy r3ROVN0hqmbrgjxXKbJibeKoj3KnUUlxpCO1lNWP159k+ficS+p6RJ7ZJ2MdKvQ/2V JDv7GKBniyP2emvJZ+TSHmE1loedETMLEUmUHSPY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Howells , Jeff Layton , Namjae Jeon , stable@kernel.org, Alexander Viro , Steve French , Hyunchul Lee , Chuck Lever , Dave Wysochanski , Linus Torvalds Subject: [PATCH 4.9 033/101] vfs: Check the truncate maximum size in inode_newsize_ok() Date: Tue, 23 Aug 2022 10:03:06 +0200 Message-Id: <20220823080035.847056784@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080034.579196046@linuxfoundation.org> References: <20220823080034.579196046@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: linux-kernel@vger.kernel.org From: David Howells commit e2ebff9c57fe4eb104ce4768f6ebcccf76bef849 upstream. If something manages to set the maximum file size to MAX_OFFSET+1, this can cause the xfs and ext4 filesystems at least to become corrupt. Ordinarily, the kernel protects against userspace trying this by checking the value early in the truncate() and ftruncate() system calls calls - but there are at least two places that this check is bypassed: (1) Cachefiles will round up the EOF of the backing file to DIO block size so as to allow DIO on the final block - but this might push the offset negative. It then calls notify_change(), but this inadvertently bypasses the checking. This can be triggered if someone puts an 8EiB-1 file on a server for someone else to try and access by, say, nfs. (2) ksmbd doesn't check the value it is given in set_end_of_file_info() and then calls vfs_truncate() directly - which also bypasses the check. In both cases, it is potentially possible for a network filesystem to cause a disk filesystem to be corrupted: cachefiles in the client's cache filesystem; ksmbd in the server's filesystem. nfsd is okay as it checks the value, but we can then remove this check too. Fix this by adding a check to inode_newsize_ok(), as called from setattr_prepare(), thereby catching the issue as filesystems set up to perform the truncate with minimal opportunity for bypassing the new check. Fixes: 1f08c925e7a3 ("cachefiles: Implement backing file wrangling") Fixes: f44158485826 ("cifsd: add file operations") Signed-off-by: David Howells Reported-by: Jeff Layton Tested-by: Jeff Layton Reviewed-by: Namjae Jeon Cc: stable@kernel.org Acked-by: Alexander Viro cc: Steve French cc: Hyunchul Lee cc: Chuck Lever cc: Dave Wysochanski Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/attr.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/attr.c +++ b/fs/attr.c @@ -111,6 +111,8 @@ EXPORT_SYMBOL(setattr_prepare); */ int inode_newsize_ok(const struct inode *inode, loff_t offset) { + if (offset < 0) + return -EINVAL; if (inode->i_size < offset) { unsigned long limit;