usbip: prevent vhci_hcd driver from leaking a socket pointer address

commit 2f2d0088eb93db5c649d2a5e34a3800a8a935fc5 upstream.

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@secunia.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 16 insertions, 10 deletions

diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h
index 9f490375ac92..f0b955f8504e 100644
--- a/drivers/usb/usbip/usbip_common.h
+++ b/drivers/usb/usbip/usbip_common.h
@@ -271,6 +271,7 @@ struct usbip_device {
 	/* lock for status */
 	spinlock_t lock;
 
+	int sockfd;
 	struct socket *tcp_socket;
 
 	struct task_struct *tcp_rx;
diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index b96e5b189269..c287ccc78fde 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -49,13 +49,17 @@ static ssize_t status_show_vhci(int pdev_nr, char *out)
 
 	/*
 	 * output example:
-	 * port sta spd dev      socket           local_busid
-	 * 0000 004 000 00000000         c5a7bb80 1-2.3
-	 * 0001 004 000 00000000         d8cee980 2-3.4
+	 * port sta spd dev      sockfd local_busid
+	 * 0000 004 000 00000000 000003 1-2.3
+	 * 0001 004 000 00000000 000004 2-3.4
 	 *
-	 * 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.
+	 * 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.
 	 */
 	for (i = 0; i < VHCI_HC_PORTS; i++) {
 		struct vhci_device *vdev = &vhci->vdev[i];
@@ -68,13 +72,13 @@ static ssize_t status_show_vhci(int pdev_nr, char *out)
 		if (vdev->ud.status == VDEV_ST_USED) {
 			out += sprintf(out, "%03u %08x ",
 					    vdev->speed, vdev->devid);
-			out += sprintf(out, "%16p %s",
-					    vdev->ud.tcp_socket,
+			out += sprintf(out, "%06u %s",
+					    vdev->ud.sockfd,
 					    dev_name(&vdev->udev->dev));
 
 		} else {
 			out += sprintf(out, "000 00000000 ");
-			out += sprintf(out, "0000000000000000 0-0");
+			out += sprintf(out, "000000 0-0");
 		}
 
 		out += sprintf(out, "\n");
@@ -125,7 +129,7 @@ static ssize_t status_show(struct device *dev,
 	int pdev_nr;
 
 	out += sprintf(out,
-		       "port sta spd dev      socket           local_busid\n");
+		       "port sta spd dev      sockfd local_busid\n");
 
 	pdev_nr = status_name_to_id(attr->attr.name);
 	if (pdev_nr < 0)
@@ -324,6 +328,7 @@ 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;