Re: [PATCH] wifi: carl9170: reject mismatched command response lengths

[Christian Lamparter <chunkeey@gmail.com>]

Hi,

On 6/28/26 11:28 AM, Yousef Alhouseen wrote:
> The firmware response length is controlled by the USB device. Although
> carl9170_cmd_callback() detects when it differs from the output buffer
> length, the function falls through and copies the entire response into
> that buffer. Callers commonly provide stack objects, so a malformed
> response can overwrite the kernel stack.
> 
> Return after scheduling device recovery. This also preserves the stated
> behavior of leaving the command incomplete so that its waiter times out
> and clears the pending output buffer.
> 
> Fixes: a84fab3cbfdc ("carl9170: 802.11 rx/tx processing and usb backend")
> Reported-by: syzbot+5c1ca6ccaa1215781cac@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=5c1ca6ccaa1215781cac
> Cc: stable@vger.kernel.org
> Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>


This was posted earlier too:
https://lore.kernel.org/linux-wireless/20260421134929.325662-1-tristmd@gmail.com/

In fact, there was even a mail before that that was sent to security@vger.kernel.org.
I told Tristan that I would much rather not return and instead fix the memcpy.
carl9170_restart can completely unbind the device, so it's unlikely that one would
see a timeout.

Cheers,
Christian


> ---
>   drivers/net/wireless/ath/carl9170/rx.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/wireless/ath/carl9170/rx.c b/drivers/net/wireless/ath/carl9170/rx.c
> index 6833430130f4..ea3f435fb64c 100644
> --- a/drivers/net/wireless/ath/carl9170/rx.c
> +++ b/drivers/net/wireless/ath/carl9170/rx.c
> @@ -145,6 +145,7 @@ static void carl9170_cmd_callback(struct ar9170 *ar, u32 len, void *buffer)
>   		 * and we get a stack trace from there.
>   		 */
>   		carl9170_restart(ar, CARL9170_RR_INVALID_RSP);
> +		return;
>   	}
>   
>   	spin_lock(&ar->cmd_lock);