USB: validate wMaxPacketValue entries in endpoint descriptors

Erroneous or malicious endpoint descriptors may have non-zero bits in
reserved positions, or out-of-bounds values.  This patch helps prevent
these from causing problems by bounds-checking the wMaxPacketValue
entries in endpoint descriptors and capping the values at the maximum
allowed.

This issue was first discovered and tests were conducted by Jake Lamberson
<jake.lamberson1@gmail.com>, an intern working for Rosie Hall.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: roswest <roswest@cisco.com>
Tested-by: roswest <roswest@cisco.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 63 insertions, 3 deletions

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 31ccdccd7a04..051163189810 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -171,6 +171,31 @@ static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
                                                         ep, buffer, size);
 }
 
+static const unsigned short low_speed_maxpacket_maxes[4] = {
+        [USB_ENDPOINT_XFER_CONTROL] = 8,
+        [USB_ENDPOINT_XFER_ISOC] = 0,
+        [USB_ENDPOINT_XFER_BULK] = 0,
+        [USB_ENDPOINT_XFER_INT] = 8,
+};
+static const unsigned short full_speed_maxpacket_maxes[4] = {
+        [USB_ENDPOINT_XFER_CONTROL] = 64,
+        [USB_ENDPOINT_XFER_ISOC] = 1023,
+        [USB_ENDPOINT_XFER_BULK] = 64,
+        [USB_ENDPOINT_XFER_INT] = 64,
+};
+static const unsigned short high_speed_maxpacket_maxes[4] = {
+        [USB_ENDPOINT_XFER_CONTROL] = 64,
+        [USB_ENDPOINT_XFER_ISOC] = 1024,
+        [USB_ENDPOINT_XFER_BULK] = 512,
+        [USB_ENDPOINT_XFER_INT] = 1023,
+};
+static const unsigned short super_speed_maxpacket_maxes[4] = {
+        [USB_ENDPOINT_XFER_CONTROL] = 512,
+        [USB_ENDPOINT_XFER_ISOC] = 1024,
+        [USB_ENDPOINT_XFER_BULK] = 1024,
+        [USB_ENDPOINT_XFER_INT] = 1024,
+};
+
 static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
     int asnum, struct usb_host_interface *ifp, int num_ep,
     unsigned char *buffer, int size)
@@ -179,6 +204,8 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
         struct usb_endpoint_descriptor *d;
         struct usb_host_endpoint *endpoint;
         int n, i, j, retval;
+        unsigned int maxp;
+        const unsigned short *maxpacket_maxes;
 
         d = (struct usb_endpoint_descriptor *) buffer;
         buffer += d->bLength;
@@ -286,6 +313,42 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
                         endpoint->desc.wMaxPacketSize = cpu_to_le16(8);
         }
 
+        /* Validate the wMaxPacketSize field */
+        maxp = usb_endpoint_maxp(&endpoint->desc);
+
+        /* Find the highest legal maxpacket size for this endpoint */
+        i = 0;          /* additional transactions per microframe */
+        switch (to_usb_device(ddev)->speed) {
+        case USB_SPEED_LOW:
+                maxpacket_maxes = low_speed_maxpacket_maxes;
+                break;
+        case USB_SPEED_FULL:
+                maxpacket_maxes = full_speed_maxpacket_maxes;
+                break;
+        case USB_SPEED_HIGH:
+                /* Bits 12..11 are allowed only for HS periodic endpoints */
+                if (usb_endpoint_xfer_int(d) || usb_endpoint_xfer_isoc(d)) {
+                        i = maxp & (BIT(12) | BIT(11));
+                        maxp &= ~i;
+                }
+                /* fallthrough */
+        default:
+                maxpacket_maxes = high_speed_maxpacket_maxes;
+                break;
+        case USB_SPEED_SUPER:
+        case USB_SPEED_SUPER_PLUS:
+                maxpacket_maxes = super_speed_maxpacket_maxes;
+                break;
+        }
+        j = maxpacket_maxes[usb_endpoint_type(&endpoint->desc)];
+
+        if (maxp > j) {
+                dev_warn(ddev, "config %d interface %d altsetting %d endpoint 0x%X has invalid maxpacket %d, setting to %d\n",
+                    cfgno, inum, asnum, d->bEndpointAddress, maxp, j);
+                maxp = j;
+                endpoint->desc.wMaxPacketSize = cpu_to_le16(i | maxp);
+        }
+
         /*
          * Some buggy high speed devices have bulk endpoints using
          * maxpacket sizes other than 512.  High speed HCDs may not
@@ -293,9 +356,6 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
          */
         if (to_usb_device(ddev)->speed == USB_SPEED_HIGH
                         && usb_endpoint_xfer_bulk(d)) {
-                unsigned maxp;
-
-                maxp = usb_endpoint_maxp(&endpoint->desc) & 0x07ff;
                 if (maxp != 512)
                         dev_warn(ddev, "config %d interface %d altsetting %d "
                                 "bulk endpoint 0x%X has invalid maxpacket %d\n",