From patchwork Tue Nov 13 05:50:16 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 996813 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-cifs-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="BG18++r5"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 42vH972mhlz9s3Z for ; Tue, 13 Nov 2018 17:02:51 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730922AbeKMP7N (ORCPT ); Tue, 13 Nov 2018 10:59:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:33038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731684AbeKMPrW (ORCPT ); Tue, 13 Nov 2018 10:47:22 -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 913732251D; Tue, 13 Nov 2018 05:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542088254; bh=qaZO47W0igsDSqRJBIAHYu4atpIPeKrqOsaUyOCM4Qw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BG18++r5ORxudZuh+kYGJtUG8XPOsgq5M3SXcAlD1ezd/RHpFNwyZDCiY6iGjGlta Ue+zeAZgEfnQz8W+KKMiOnymau+TkWsvOv4USbx1q8YOPakp4jxAsBF2YEp3Qe/2JI Dm23PRcxixfjV7vyuzGpzXAbRROuyJ4gNDH2ll6s= 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 4.18 02/39] cifs: don't dereference smb_file_target before null check Date: Tue, 13 Nov 2018 00:50:16 -0500 Message-Id: <20181113055053.78352-2-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181113055053.78352-1-sashal@kernel.org> References: <20181113055053.78352-1-sashal@kernel.org> Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org 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 69ec5427769c..9c194593270b 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -984,8 +984,8 @@ 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; @@ -999,6 +999,9 @@ 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