Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1579910

Re: [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer

Show all headers | View raw

On Mon, Feb 13 2017, Gustavo A. R. Silva wrote:
> Rewrite udc_free_dma_chain() function to avoid use of pointer after free.
>
> Addresses-Coverity-ID: 1091172
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>

Acked-by: Michal Nazarewicz <mina86@mina86.com>

> ---
>  drivers/usb/gadget/udc/amd5536udc.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/gadget/udc/amd5536udc.c b/drivers/usb/gadget/udc/amd5536udc.c
> index ea03ca7..ded97a3 100644
> --- a/drivers/usb/gadget/udc/amd5536udc.c
> +++ b/drivers/usb/gadget/udc/amd5536udc.c
> @@ -611,21 +611,23 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
>  static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
>  {
>  	int ret_val = 0;
> -	struct udc_data_dma	*td;
> -	struct udc_data_dma	*td_last = NULL;
> +	struct udc_data_dma *td = req->td_data;
>  	unsigned int i;
>  
> +	dma_addr_t addr_aux = 0x00;

Perhaps call it ‘addr_next’ or ‘next’?

> +	dma_addr_t addr = (dma_addr_t)td->next;
> +	td->next = 0x00;
> +
>  	DBG(dev, "free chain req = %p\n", req);
>  
>  	/* do not free first desc., will be done by free for request */
> -	td_last = req->td_data;
> -	td = phys_to_virt(td_last->next);
> -
>  	for (i = 1; i < req->chain_len; i++) {
> -		pci_pool_free(dev->data_requests, td,
> -			      (dma_addr_t)td_last->next);
> -		td_last = td;
> -		td = phys_to_virt(td_last->next);
> +		td = phys_to_virt(addr);
> +		addr_aux = (dma_addr_t)td->next;
> +		td->next = 0x00;

This is unnecessary.

> +		pci_pool_free(dev->data_requests, td, addr);
> +		td = NULL;

Ditto.

> +		addr = addr_aux;
>  	}
>  
>  	return ret_val;
> -- 
> 2.5.0
>

-- 
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/2] avoid use of freed pointer "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-13 16:40 +0100
  [PATCH 2/2] usb: gadget: udc: remove unnecessary variable and update  function prototype "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-13 17:10 +0100
    Re: [PATCH 2/2] usb: gadget: udc: remove unnecessary variable and update function prototype Michal Nazarewicz <mina86@mina86.com> - 2017-02-13 17:10 +0100
  Re: [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer Michal Nazarewicz <mina86@mina86.com> - 2017-02-13 17:10 +0100
    Re: [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-14 23:00 +0100
      [PATCH v2 1/2] usb: gadget: udc: avoid use of freed pointer "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-14 23:00 +0100
        [PATCH v2 2/2] usb: gadget: udc: remove unnecessary variable and  update function prototype "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-14 23:10 +0100
  [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-02-13 17:10 +0100

csiph-web