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

From: Shuah Khan
Date: Mon Feb 05 2018 - 12:46:57 EST


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