From patchwork Tue Nov 13 05:51:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 10679689 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 361EA109C for ; Tue, 13 Nov 2018 05:58:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2353B29FAC for ; Tue, 13 Nov 2018 05:58:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 160A02A264; Tue, 13 Nov 2018 05:58:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A0C1C29FAC for ; Tue, 13 Nov 2018 05:58:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732482AbeKMPsT (ORCPT ); Tue, 13 Nov 2018 10:48:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:34606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732472AbeKMPsT (ORCPT ); Tue, 13 Nov 2018 10:48:19 -0500 Received: from sasha-vm.mshome.net (unknown [64.114.255.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 540A722521; Tue, 13 Nov 2018 05:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542088311; bh=KIq0agkofycnTeUH1BtNPsId2qWd8cbFlCewcHK8oyg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jgjrxBv9WEw666qT9gd3gKfWFs5Hp5Uer7/1eJQS7nKVyiQ57OGjxgVZlj8EXDoYX CroM/u8S1gRtb+k/ncL+5xbp03fkM8oHTdIulffEHmLihr0lbHiQWinWIJoE8mksct IBHWPKPJ6Ljfik9sR4D/0aATEVENGoUzCXLncCEI= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Colin Ian King , Steve French , Sasha Levin , linux-cifs@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 02/26] cifs: don't dereference smb_file_target before null check Date: Tue, 13 Nov 2018 00:51:26 -0500 Message-Id: <20181113055150.78773-2-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181113055150.78773-1-sashal@kernel.org> References: <20181113055150.78773-1-sashal@kernel.org> Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Colin Ian King [ Upstream commit 8c6c9bed8773375b1d54ccca2911ec892c59db5d ] There is a null check on dst_file->private data which suggests it can be potentially null. However, before this check, pointer smb_file_target is derived from dst_file->private and dereferenced in the call to tlink_tcon, hence there is a potential null pointer deference. Fix this by assigning smb_file_target and target_tcon after the null pointer sanity checks. Detected by CoverityScan, CID#1475302 ("Dereference before null check") Fixes: 04b38d601239 ("vfs: pull btrfs clone API to vfs layer") Signed-off-by: Colin Ian King Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/cifs/cifsfs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 44a7b2dea688..c5fd5abf7206 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -933,8 +933,8 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off, struct inode *src_inode = file_inode(src_file); struct inode *target_inode = file_inode(dst_file); struct cifsFileInfo *smb_file_src = src_file->private_data; - struct cifsFileInfo *smb_file_target = dst_file->private_data; - struct cifs_tcon *target_tcon = tlink_tcon(smb_file_target->tlink); + struct cifsFileInfo *smb_file_target; + struct cifs_tcon *target_tcon; unsigned int xid; int rc; @@ -948,6 +948,9 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off, goto out; } + smb_file_target = dst_file->private_data; + target_tcon = tlink_tcon(smb_file_target->tlink); + /* * Note: cifs case is easier than btrfs since server responsible for * checks for proper open modes and file type and if it wants