[PATCH] USB: usblp: return error when setting unsupported protocol

[PATCH] USB: usblp: return error when setting unsupported protocol

[Jun Yan]

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 0.

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")
Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
---
 drivers/usb/class/usblp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 5a2e43331064..ff1a941fd2ed 100644
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -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;
 
+	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) {
-		alts = usblp->protocol[protocol].alt_setting;
-		if (alts < 0)
-			return -EINVAL;
 		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",
-- 
2.47.1

Re: [PATCH] USB: usblp: return error when setting unsupported protocol

[Greg KH]

On Wed, Dec 11, 2024 at 11:42:43PM +0800, Jun Yan wrote:
> 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 0.
> 
> 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")
> Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
> ---
>  drivers/usb/class/usblp.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
> index 5a2e43331064..ff1a941fd2ed 100644
> --- a/drivers/usb/class/usblp.c
> +++ b/drivers/usb/class/usblp.c
> @@ -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;
>  
> +	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) {
> -		alts = usblp->protocol[protocol].alt_setting;
> -		if (alts < 0)
> -			return -EINVAL;
>  		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",
> -- 
> 2.47.1
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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