[PATCH 4.4 v2 2/2] usbip: fix 3eee23c3ec14 tcp_socket address still in the status file

[Shuah Khan]

Commit 3eee23c3ec14 ("usbip: prevent vhci_hcd driver from leaking a
socket pointer address") backported the following commit from mailine.
However, backport error caused the tcp_socket address to still leak.

commit 2f2d0088eb93 ("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: Eric Biggers <ebiggers3@xxxxxxxxx>
Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
---
 drivers/usb/usbip/vhci_sysfs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index 1c7f41a65565..b9432fdec775 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -53,7 +53,7 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 	 * a security hole, the change is made to use sockfd instead.
 	 */
 	out += sprintf(out,
-		       "prt sta spd bus dev sockfd local_busid\n");
+		       "prt sta spd dev      sockfd local_busid\n");
 
 	for (i = 0; i < VHCI_NPORTS; i++) {
 		struct vhci_device *vdev = port_to_vdev(i);
@@ -64,12 +64,11 @@ 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, "%06u", vdev->ud.sockfd);
+			out += sprintf(out, "%06u ", vdev->ud.sockfd);
 			out += sprintf(out, "%s", dev_name(&vdev->udev->dev));
 
 		} else
-			out += sprintf(out, "000 000 000 000000 0-0");
+			out += sprintf(out, "000 00000000 000000 0-0");
 
 		out += sprintf(out, "\n");
 		spin_unlock(&vdev->ud.lock);
-- 
2.14.1