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Commit 01af472c authored by Jun Yan's avatar Jun Yan Committed by Greg Kroah-Hartman
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USB: usblp: return error when setting unsupported protocol 



commit 7a3d76a0b60b3f6fc3375e4de2174bab43f64545 upstream.

Fix the regression introduced by commit d8c6edfa3f4e ("USB:
usblp: don't call usb_set_interface if there's a single alt"),
which causes that unsupported protocols can also be set via
ioctl when the num_altsetting of the device is 1.

Move the check for protocol support to the earlier stage.

Fixes: d8c6edfa3f4e ("USB: usblp: don't call usb_set_interface if there's a single alt")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarJun Yan <jerrysteve1101@gmail.com>
Link: https://lore.kernel.org/r/20241212143852.671889-1-jerrysteve1101@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f5f33fb5

drivers/usb/class/usblp.c

+4 −3
Original line number Diff line number Diff line
@@ -1337,11 +1337,12 @@ static int usblp_set_protocol(struct usblp *usblp, int protocol) 
	if (protocol < USBLP_FIRST_PROTOCOL || protocol > USBLP_LAST_PROTOCOL)

		return -EINVAL;



	/* Don't unnecessarily set the interface if there's a single alt. */

	if (usblp->intf->num_altsetting > 1) {

	alts = usblp->protocol[protocol].alt_setting;

	if (alts < 0)

		return -EINVAL;



	/* Don't unnecessarily set the interface if there's a single alt. */

	if (usblp->intf->num_altsetting > 1) {

		r = usb_set_interface(usblp->dev, usblp->ifnum, alts);

		if (r < 0) {

			printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",