linux-kernel - Re: [PATCH v2 1/2] usb: cdns3: fixed memory use after free at cdns3_gadget_ep

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Date: Mon, 5 Feb 2024 12:43:00 +0800
From: Peter Chen <peter.chen@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: rogerq@...nel.org, felipe.balbi@...ux.intel.com,
	gregkh@...uxfoundation.org, imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	pawell@...ence.com
Subject: Re: [PATCH v2 1/2] usb: cdns3: fixed memory use after free at
 cdns3_gadget_ep_disable()

On 24-02-02 10:42:16, Frank Li wrote:
>   ...
>   cdns3_gadget_ep_free_request(&priv_ep->endpoint, &priv_req->request);
>   list_del_init(&priv_req->list);
>   ...
> 
> 'priv_req' actually free at cdns3_gadget_ep_free_request(). But
> list_del_init() use priv_req->list after it.
> 
> [ 1542.642868][  T534] BUG: KFENCE: use-after-free read in __list_del_entry_valid+0x10/0xd4
> [ 1542.642868][  T534]
> [ 1542.653162][  T534] Use-after-free read at 0x000000009ed0ba99 (in kfence-#3):
> [ 1542.660311][  T534]  __list_del_entry_valid+0x10/0xd4
> [ 1542.665375][  T534]  cdns3_gadget_ep_disable+0x1f8/0x388 [cdns3]
> [ 1542.671571][  T534]  usb_ep_disable+0x44/0xe4
> [ 1542.675948][  T534]  ffs_func_eps_disable+0x64/0xc8
> [ 1542.680839][  T534]  ffs_func_set_alt+0x74/0x368
> [ 1542.685478][  T534]  ffs_func_disable+0x18/0x28
> 
> Move list_del_init() before cdns3_gadget_ep_free_request() to resolve this
> problem.
> 
> Cc: <stable@...r.kernel.org>
> Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
> Signed-off-by: Frank Li <Frank.Li@....com>
> Reviewed-by: Roger Quadros <rogerq@...nel.org>

Acked-by: Peter Chen <peter.chen@...nel.org>

> ---
>  drivers/usb/cdns3/cdns3-gadget.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
> index aeca902ab6cc4..d6723d31fc6e2 100644
> --- a/drivers/usb/cdns3/cdns3-gadget.c
> +++ b/drivers/usb/cdns3/cdns3-gadget.c
> @@ -2540,11 +2540,11 @@ 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);
>  		--priv_ep->wa2_counter;
>  	}
>  
> -- 
> 2.34.1
> 

-- 

Thanks,
Peter Chen