[PATCH 3.18 2/9] usbip: fix stub_rx: harden CMD_SUBMIT path to handle malicious input

Shuah Khan
2018-02-07T21:20:25Z

Upstream commit c6688ef9f297 ("usbip: fix stub_rx: harden CMD_SUBMIT path
to handle malicious input")

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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/usbip/stub_rx.c | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
index 2e07acda456e..f5533c99cd48 100644
--- a/drivers/usb/usbip/stub_rx.c
+++ b/drivers/usb/usbip/stub_rx.c
@@ -341,11 +341,13 @@ 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;
@@ -358,6 +360,7 @@ static int get_pipe(struct stub_device *sdev, int epnum, int dir)
goto err_ret;

epd = &ep->desc;
+
if (usb_endpoint_xfer_control(epd)) {
if (dir == USBIP_DIR_OUT)
return usb_sndctrlpipe(udev, epnum);
@@ -380,6 +383,27 @@ 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;
+
+#define USB_EP_MAXP_MULT_SHIFT 11
+#define USB_EP_MAXP_MULT_MASK (3 << USB_EP_MAXP_MULT_SHIFT)
+#define USB_EP_MAXP_MULT(m) \
+ (((m) & USB_EP_MAXP_MULT_MASK) >> USB_EP_MAXP_MULT_SHIFT)
+
+ maxp = usb_endpoint_maxp(epd);
+ maxp *= (USB_EP_MAXP_MULT(
+ __le16_to_cpu(epd->wMaxPacketSize)) + 1);
+ 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->udev->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
@@ -388,7 +412,7 @@ static int get_pipe(struct stub_device *sdev, int epnum, int dir)

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

@@ -453,7 +477,7 @@ 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;
--
2.14.1