usbip: fix stub_rx: harden CMD_SUBMIT path to handle malicious input

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>

diff --git a/drivers/staging/usbip/stub_rx.c b/drivers/staging/usbip/stub_rx.c
index b4477a5..22d9331 100644 (file)
--- 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(struct stub_device *sdev,
        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 *sdev, int epnum, int dir)
                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 *sdev, int epnum, int dir)
        }
 
        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 *sdev, int epnum, int dir)
 
 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 stub_device *sdev,
        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 stub_device *sdev,
        }
 
        /* 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);