Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754643AbcDJUIE (ORCPT ); Sun, 10 Apr 2016 16:08:04 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53255 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759588AbcDJS6q (ORCPT ); Sun, 10 Apr 2016 14:58:46 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Douglas Gilbert , Ewan Milne , "Martin K. Petersen" Subject: [PATCH 4.4 038/210] sg: fix dxferp in from_to case Date: Sun, 10 Apr 2016 11:34:19 -0700 Message-Id: <20160410183528.019869346@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183526.651820045@linuxfoundation.org> References: <20160410183526.651820045@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1844 Lines: 47 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Douglas Gilbert commit 5ecee0a3ee8d74b6950cb41e8989b0c2174568d4 upstream. One of the strange things that the original sg driver did was let the user provide both a data-out buffer (it followed the sg_header+cdb) _and_ specify a reply length greater than zero. What happened was that the user data-out buffer was copied into some kernel buffers and then the mid level was told a read type operation would take place with the data from the device overwriting the same kernel buffers. The user would then read those kernel buffers back into the user space. >From what I can tell, the above action was broken by commit fad7f01e61bf ("sg: set dxferp to NULL for READ with the older SG interface") in 2008 and syzkaller found that out recently. Make sure that a user space pointer is passed through when data follows the sg_header structure and command. Fix the abnormal case when a non-zero reply_len is also given. Fixes: fad7f01e61bf737fe8a3740d803f000db57ecac6 Signed-off-by: Douglas Gilbert Reviewed-by: Ewan Milne Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sg.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -652,7 +652,8 @@ sg_write(struct file *filp, const char _ else hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE; hp->dxfer_len = mxsize; - if (hp->dxfer_direction == SG_DXFER_TO_DEV) + if ((hp->dxfer_direction == SG_DXFER_TO_DEV) || + (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV)) hp->dxferp = (char __user *)buf + cmd_size; else hp->dxferp = NULL;