Re: [PATCH] usb: cdns3: Do not access memory after free

[Marek Vasut <marex@nabladev.com>]

On 8/13/25 6:30 PM, Andrew Goodbody wrote:
> The call to cdns3_gadget_ep_free_request will free priv_req so do the
> call to list_del_init which accesses the memory pointed to by priv_req
> before the free.
> 
> This issue was found by Smatch.
> 
> Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
> ---
>   drivers/usb/cdns3/gadget.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> index a30c40ef80e..9eaf7e40ab6 100644
> --- a/drivers/usb/cdns3/gadget.c
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -557,10 +557,10 @@ static void cdns3_wa2_remove_old_request(struct cdns3_endpoint *priv_ep)
>   
>   		trace_cdns3_wa2(priv_ep, "removes eldest request");
>   
> +		list_del_init(&priv_req->list);
>   		kfree(priv_req->request.buf);
>   		cdns3_gadget_ep_free_request(&priv_ep->endpoint,
>   					     &priv_req->request);
> -		list_del_init(&priv_req->list);

Shouldn't the kfree() be moved here instead ? 
cdns3_gadget_ep_free_request() also accesses priv_req->request .

>   		--priv_ep->wa2_counter;
>   
>   		if (!chain)
> @@ -1959,10 +1959,10 @@ static int cdns3_gadget_ep_disable(struct usb_ep *ep)
>   	while (!list_empty(&priv_ep->wa2_descmiss_req_list)) {
>   		priv_req = cdns3_next_priv_request(&priv_ep->wa2_descmiss_req_list);
>   
> +		list_del_init(&priv_req->list);
>   		kfree(priv_req->request.buf);
>   		cdns3_gadget_ep_free_request(&priv_ep->endpoint,
>   					     &priv_req->request);
> -		list_del_init(&priv_req->list);

DTTO ?