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USB: serial: qcserial: fix altsetting probing 

Drivers should not assume that interface descriptors have been parsed in
any particular order so use the interface number to look up the second
alternate setting. That number is also what the driver later use to
switch setting.

Note that although the driver could end up verifying the existence of
the expected endpoints on the wrong interface, a later sanity check in
usb_wwan_port_probe() would have caught this before it could cause any
real damage.

Fixes: a78b42824d ("USB: serial: add qualcomm wireless modem driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2020-09-29 12:42:39 +02:00
parent 75240ac439
commit be4c5eb267
1 changed files with 2 additions and 2 deletions
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4
drivers/usb/serial/qcserial.c
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@ -243,11 +243,11 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
/* QDL mode */
/* Gobi 2000 has a single altsetting, older ones have two */
if (serial->interface->num_altsetting == 2)
intf = &serial->interface->altsetting[1];
intf = usb_altnum_to_altsetting(serial->interface, 1);
else if (serial->interface->num_altsetting > 2)
goto done;
if (intf->desc.bNumEndpoints == 2 &&
if (intf && intf->desc.bNumEndpoints == 2 &&
usb_endpoint_is_bulk_in(&intf->endpoint[0].desc) &&
usb_endpoint_is_bulk_out(&intf->endpoint[1].desc)) {
dev_dbg(dev, "QDL port found\n");