releases/4.4.18/ipath-restrict-use-of-the-write-interface.patch

From ben@decadent.org.uk  Sun Aug 14 16:54:26 2016
From: Ben Hutchings <ben@decadent.org.uk>
Date: Tue, 31 May 2016 03:33:57 +0100
Subject: ipath: Restrict use of the write() interface
To: stable@vger.kernel.org
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>, Doug Ledford <dledford@redhat.com>, linux-rdma@vger.kernel.org
Message-ID: <20160531023356.GI7555@decadent.org.uk>
Content-Disposition: inline

From: Ben Hutchings <ben@decadent.org.uk>

Commit e6bd18f57aad ("IB/security: Restrict use of the write()
interface") fixed a security problem with various write()
implementations in the Infiniband subsystem.  In older kernel versions
the ipath_write() function has the same problem and needs the same
restriction.  (The ipath driver has been completely removed upstream.)

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/rdma/ipath/ipath_file_ops.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/staging/rdma/ipath/ipath_file_ops.c
+++ b/drivers/staging/rdma/ipath/ipath_file_ops.c
@@ -45,6 +45,8 @@
 #include <linux/uio.h>
 #include <asm/pgtable.h>
 
+#include <rdma/ib.h>
+
 #include "ipath_kernel.h"
 #include "ipath_common.h"
 #include "ipath_user_sdma.h"
@@ -2243,6 +2245,9 @@ static ssize_t ipath_write(struct file *
 	ssize_t ret = 0;
 	void *dest;
 
+	if (WARN_ON_ONCE(!ib_safe_file_access(fp)))
+		return -EACCES;
+
 	if (count < sizeof(cmd.type)) {
 		ret = -EINVAL;
 		goto bail;