usb: usb_parse_endpoint ignore reserved bits

Reading bEndpointAddress the spec tells is
that

b7 is direction, which must be ignored
b6:4 are reserved which are to be set to zero b3:0 are the endpoint address

In order to be backwards compatible with possible future versions of USB we have to be ready with devices using those bits. That means that we also have to ignore them like we do with the direction bit.
In consequence the only illegal address you can encoding in four bits is endpoint zero, for which no descriptor must exist. Hence the check for exceeding the upper limit on endpoint addresses is removed.

Signed-off-by Oliver Neukum <[email protected]>

---

v2: Improved commit log
v3: Symbolic mask and improved error message

 drivers/usb/core/config.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/usb/core/config.c +4 -4

index 7f8d33f92ddb..3362af165ef5 100644
@@ -279,11 +279,11 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno,
 		goto skip_to_next_endpoint_or_interface_descriptor;
 	}
 
-	i = d->bEndpointAddress & ~USB_ENDPOINT_DIR_MASK;
-	if (i >= 16 || i == 0) {
+	i = d->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
+	if (i == 0) {
 		dev_notice(ddev, "config %d interface %d altsetting %d has an "
-		    "invalid endpoint with address 0x%X, skipping\n",
-		    cfgno, inum, asnum, d->bEndpointAddress);
+		    "invalid descriptor for endpoint zero, skipping\n",
+		    cfgno, inum, asnum);
 		goto skip_to_next_endpoint_or_interface_descriptor;
 	}
 

Signature · 1 line

2.44.0