[PATCH 3.2 74/79] usbip: fix stub_rx: harden CMD_SUBMIT path to handle malicious input

Ben Hutchings
2018-02-11T04:33:41Z

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

commit c6688ef9f29762e65bce325ef4acd6c675806366 upstream.

Harden CMD_SUBMIT path to handle malicious input that could trigger
large memory allocations. Add checks to validate transfer_buffer_length
and number_of_packets to protect against bad input requesting for
unbounded memory allocations. Validate early in get_pipe() and return
failure.

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:
- Device for logging purposes is &sdev->interface->dev
- Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/staging/usbip/stub_rx.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)

--- a/drivers/staging/usbip/stub_rx.c
+++ b/drivers/staging/usbip/stub_rx.c
@@ -350,11 +350,13 @@ static struct stub_priv *stub_priv_alloc
return priv;
}

-static int get_pipe(struct stub_device *sdev, int epnum, int dir)
+static int get_pipe(struct stub_device *sdev, struct usbip_header *pdu)
{
struct usb_device *udev = sdev->udev;
struct usb_host_endpoint *ep;
struct usb_endpoint_descriptor *epd = NULL;
+ int epnum = pdu->base.ep;
+ int dir = pdu->base.direction;

if (epnum < 0 || epnum > 15)
goto err_ret;
@@ -367,6 +369,15 @@ static int get_pipe(struct stub_device *
goto err_ret;

epd = &ep->desc;
+
+ /* validate transfer_buffer_length */
+ if (pdu->u.cmd_submit.transfer_buffer_length > INT_MAX) {
+ dev_err(&sdev->interface->dev,
+ "CMD_SUBMIT: -EMSGSIZE transfer_buffer_length %d\n",
+ pdu->u.cmd_submit.transfer_buffer_length);
+ return -1;
+ }
+
if (usb_endpoint_xfer_control(epd)) {
if (dir == USBIP_DIR_OUT)
return usb_sndctrlpipe(udev, epnum);
@@ -389,6 +400,21 @@ static int get_pipe(struct stub_device *
}

if (usb_endpoint_xfer_isoc(epd)) {
+ /* validate packet size and number of packets */
+ unsigned int maxp, packets, bytes;
+
+ maxp = usb_endpoint_maxp(epd);
+ maxp *= usb_endpoint_maxp_mult(epd);
+ bytes = pdu->u.cmd_submit.transfer_buffer_length;
+ packets = DIV_ROUND_UP(bytes, maxp);
+
+ if (pdu->u.cmd_submit.number_of_packets < 0 ||
+ pdu->u.cmd_submit.number_of_packets > packets) {
+ dev_err(&sdev->interface->dev,
+ "CMD_SUBMIT: isoc invalid num packets %d\n",
+ pdu->u.cmd_submit.number_of_packets);
+ return -1;
+ }
if (dir == USBIP_DIR_OUT)
return usb_sndisocpipe(udev, epnum);
else
@@ -397,7 +423,7 @@ static int get_pipe(struct stub_device *

err_ret:
/* NOT REACHED */
- dev_err(&sdev->interface->dev, "get pipe() invalid epnum %d\n", epnum);
+ dev_err(&sdev->interface->dev, "CMD_SUBMIT: invalid epnum %d\n", epnum);
return -1;
}

@@ -462,7 +488,7 @@ static void stub_recv_cmd_submit(struct
struct stub_priv *priv;
struct usbip_device *ud = &sdev->ud;
struct usb_device *udev = sdev->udev;
- int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);
+ int pipe = get_pipe(sdev, pdu);

if (pipe == -1)
return;
@@ -485,7 +511,8 @@ static void stub_recv_cmd_submit(struct
}

/* set priv->urb->transfer_buffer */
- if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
+ if (pdu->u.cmd_submit.transfer_buffer_length > 0 &&
+ pdu->u.cmd_submit.transfer_buffer_length <= INT_MAX) {
priv->urb->transfer_buffer =
kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
GFP_KERNEL);