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.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-by: roswest <roswest@xxxxxxxxx>
Tested-by: roswest <roswest@xxxxxxxxx>
---
I don't think this needs to go into the -stable kernels, but if anyone
disagrees I won't object.
[as1806]
drivers/usb/core/config.c | 66 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 63 insertions(+), 3 deletions(-)
Index: usb-4.x/drivers/usb/core/config.c
===================================================================
--- usb-4.x.orig/drivers/usb/core/config.c
+++ usb-4.x/drivers/usb/core/config.c
@@ -171,6 +171,31 @@ static void usb_parse_ss_endpoint_compan
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 dev
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;
@@ -290,6 +317,42 @@ static int usb_parse_endpoint(struct dev
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
@@ -297,9 +360,6 @@ static int usb_parse_endpoint(struct dev
*/
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",
--
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