From patchwork Mon Sep 2 15:10:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Colin King X-Patchwork-Id: 11126877 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E82581510 for ; Mon, 2 Sep 2019 15:11:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2255217F4 for ; Mon, 2 Sep 2019 15:11:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731700AbfIBPLC (ORCPT ); Mon, 2 Sep 2019 11:11:02 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42056 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730708AbfIBPLC (ORCPT ); Mon, 2 Sep 2019 11:11:02 -0400 Received: from 1.general.cking.uk.vpn ([10.172.193.212] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i4nyu-0000hR-7J; Mon, 02 Sep 2019 15:11:00 +0000 From: Colin King To: Steve French , linux-cifs@vger.kernel.org, samba-technical@lists.samba.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH][V2][cifs-next] cifs: fix dereference on ses before it is null checked Date: Mon, 2 Sep 2019 16:10:59 +0100 Message-Id: <20190902151059.22088-1-colin.king@canonical.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org From: Colin Ian King The assignment of pointer server dereferences pointer ses, however, this dereference occurs before ses is null checked and hence we have a potential null pointer dereference. Fix this by only dereferencing ses after it has been null checked. Addresses-Coverity: ("Dereference before null check") Fixes: 2808c6639104 ("cifs: add new debugging macro cifs_server_dbg") Signed-off-by: Colin Ian King --- fs/cifs/smb2pdu.c | 11 ++++++++--- fs/cifs/transport.c | 3 ++- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index dbc6ef50dd45..0e92983de0b7 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -2759,8 +2759,10 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid, else return -EIO; + if (!ses) + return -EIO; server = ses->server; - if (!ses || !(server)) + if (!server) return -EIO; if (smb3_encryption_required(tcon)) @@ -3058,13 +3060,16 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon, int rc = 0; int resp_buftype = CIFS_NO_BUFFER; struct cifs_ses *ses = tcon->ses; - struct TCP_Server_Info *server = ses->server; + struct TCP_Server_Info *server; int flags = 0; bool allocated = false; cifs_dbg(FYI, "Query Info\n"); - if (!ses || !(server)) + if (!ses) + return -EIO; + server = ses->server; + if (!server) return -EIO; if (smb3_encryption_required(tcon)) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 0d60bd2f4dca..a90bd4d75b4d 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -1242,12 +1242,13 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses, struct kvec iov = { .iov_base = in_buf, .iov_len = len }; struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 }; struct cifs_credits credits = { .value = 1, .instance = 0 }; - struct TCP_Server_Info *server = ses->server; + struct TCP_Server_Info *server; if (ses == NULL) { cifs_dbg(VFS, "Null smb session\n"); return -EIO; } + server = ses->server; if (server == NULL) { cifs_dbg(VFS, "Null tcp session\n"); return -EIO;