[PATCH 3.2 75/79] usbip: prevent vhci_hcd driver from leaking a socket pointer address

Ben Hutchings
2018-02-11T04:20:06Z

From: Shuah Khan <shuahkh@osg.samsung.com>

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>
[bwh: Backported to 3.2:
- usbip port status does not include hub type
- Adjust filenames, context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/staging/usbip/usbip_common.h | 1 +
drivers/staging/usbip/vhci_sysfs.c | 25 ++++++++++++++++---------
drivers/staging/usbip/userspace/libsrc/vhci_driver.c | 8 ++++----
3 files changed, 21 insertions(+), 13 deletions(-)

--- 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;
--- a/drivers/staging/usbip/vhci_sysfs.c
+++ b/drivers/staging/usbip/vhci_sysfs.c
@@ -38,13 +38,18 @@ static ssize_t show_status(struct device

/*
* 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 "
"local_busid\n");
@@ -58,7 +63,7 @@ static ssize_t show_status(struct device
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, "%u", vdev->ud.sockfd);
out += sprintf(out, "%s", dev_name(&vdev->udev->dev));

} else {
@@ -215,6 +220,7 @@ static ssize_t store_attach(struct devic

vdev->devid = devid;
vdev->speed = speed;
+ vdev->ud.sockfd = sockfd;
vdev->ud.tcp_socket = socket;
vdev->ud.status = VDEV_ST_NOTASSIGNED;

--- a/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
+++ b/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
@@ -63,12 +63,12 @@ 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 %31s\n",
+ ret = sscanf(c, "%d %d %d %x %u %31s\n",
&port, &status, &speed,
- &devid, &socket, lbusid);
+ &devid, &sockfd, lbusid);

if (ret < 5) {
dbg("sscanf failed: %d", ret);
@@ -77,7 +77,7 @@ 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 */