[Trusty SRU] Fix for CVE-2017-16911

[Stefan Bader]

>From d9048d4e4a99354071874d7df13300275a0e2884 Mon Sep 17 00:00:00 2001
From: Shuah Khan <shuahkh at osg.samsung.com>
Date: Thu, 7 Dec 2017 14:16:49 -0700
Subject: [PATCH] usbip: prevent vhci_hcd driver from leaking a socket pointer
 address

When a client has a USB device attached over IP, the vhci_hcd driver is
locally leaking a socket pointer address via the

/sys/devices/platform/vhci_hcd/status file (world-readable) and in debug
output when "usbip --debug port" is run.

Fix it to not leak. The socket pointer address is not used at the moment
and it was made visible as a convenient way to find IP address from socket
pointer address by looking up /proc/net/{tcp,tcp6}.

As this opens a security hole, the fix replaces socket pointer address with
sockfd.

Reported-by: Secunia Research <vuln at secunia.com>
Cc: stable <stable at vger.kernel.org>
Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

CVE-2017-16911

(backported from commit 2f2d0088eb93db5c649d2a5e34a3800a8a935fc5)
[smb: driver still in staging, adapted to different output format]
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---

The driver is in staging still and also used a different output format.
I believe this should cover the original approach and is compile tested
on x86_64.

-Stefan

 drivers/staging/usbip/usbip_common.h               |  1 +
 .../staging/usbip/userspace/libsrc/vhci_driver.c   |  8 ++++----
 drivers/staging/usbip/vhci_sysfs.c                 | 22 ++++++++++++++--------
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/usbip/usbip_common.h b/drivers/staging/usbip/usbip_common.h
index 7e6c543..3eb8038 100644
--- a/drivers/staging/usbip/usbip_common.h
+++ b/drivers/staging/usbip/usbip_common.h
@@ -276,6 +276,7 @@ struct usbip_device {
 	/* lock for status */
 	spinlock_t lock;
 
+	int sockfd;
 	struct socket *tcp_socket;
 
 	struct task_struct *tcp_rx;
diff --git a/drivers/staging/usbip/userspace/libsrc/vhci_driver.c b/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
index 1091bb2..f86d3c8 100644
--- a/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
+++ b/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
@@ -69,12 +69,12 @@ static int parse_status(char *value)
 
 	while (*c != '\0') {
 		int port, status, speed, devid;
-		unsigned long socket;
+		int sockfd;
 		char lbusid[SYSFS_BUS_ID_SIZE];
 
-		ret = sscanf(c, "%d %d %d %x %lx %s\n",
+		ret = sscanf(c, "%d %d %d %x %u %s\n",
 				&port, &status, &speed,
-				&devid, &socket, lbusid);
+				&devid, &sockfd, lbusid);
 
 		if (ret < 5) {
 			dbg("sscanf failed: %d", ret);
@@ -83,7 +83,7 @@ static int parse_status(char *value)
 
 		dbg("port %d status %d speed %d devid %x",
 				port, status, speed, devid);
-		dbg("socket %lx lbusid %s", socket, lbusid);
+		dbg("sockfd %u lbusid %s", sockfd, lbusid);
 
 
 		/* if a device is connected, look at it */
diff --git a/drivers/staging/usbip/vhci_sysfs.c b/drivers/staging/usbip/vhci_sysfs.c
index 9b51586..db057c3 100644
--- a/drivers/staging/usbip/vhci_sysfs.c
+++ b/drivers/staging/usbip/vhci_sysfs.c
@@ -39,15 +39,20 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 
 	/*
 	 * output example:
-	 * prt sta spd dev socket           local_busid
-	 * 000 004 000 000         c5a7bb80 1-2.3
-	 * 001 004 000 000         d8cee980 2-3.4
+	 * prt sta spd dev sockfd    local_busid
+	 * 000 004 000 000 3         1-2.3
+	 * 001 004 000 000 4         2-3.4
+	 *
+	 * Output includes socket fd instead of socket pointer address to avoid
+	 * leaking kernel memory address in:
+	 *     /sys/devices/platform/vhci_hcd.0/status and in debug output.
+	 * The socket pointer address is not used at the moment and it was made
+	 * visible as a convenient way to find IP address from socket pointer
+	 * address by looking up /proc/net/{tcp,tcp6}. As this opens a security
+	 * hole, the change is made to use sockfd instead.
 	 *
-	 * IP address can be retrieved from a socket pointer address by looking
-	 * up /proc/net/{tcp,tcp6}. Also, a userland program may remember a
-	 * port number and its peer IP address.
 	 */
-	out += sprintf(out, "prt sta spd bus dev socket           "
+	out += sprintf(out, "prt sta spd bus dev sockfd    "
 		       "local_busid\n");
 
 	for (i = 0; i < VHCI_NPORTS; i++) {
@@ -59,7 +64,7 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 		if (vdev->ud.status == VDEV_ST_USED) {
 			out += sprintf(out, "%03u %08x ",
 				       vdev->speed, vdev->devid);
-			out += sprintf(out, "%16p ", vdev->ud.tcp_socket);
+			out += sprintf(out, "%9u ", vdev->ud.sockfd);
 			out += sprintf(out, "%s", dev_name(&vdev->udev->dev));
 
 		} else {
@@ -219,6 +224,7 @@ static ssize_t store_attach(struct device *dev, struct device_attribute *attr,
 
 	vdev->devid         = devid;
 	vdev->speed         = speed;
+	vdev->ud.sockfd     = sockfd;
 	vdev->ud.tcp_socket = socket;
 	vdev->ud.status     = VDEV_ST_NOTASSIGNED;
 
-- 
2.7.4