Re: [PATCH v2] usb: gadget: udc: remove pointer dereference after free

[Gustavo A. R. Silva]

Hi Michal,

Quoting Michal Nazarewicz <mina86@xxxxxxxxxx>:

> On Sat, Feb 11 2017, Gustavo A. R. Silva wrote:
> > Remove pointer dereference after free and set pointer to NULL after free.
> >
> > Addresses-Coverity-ID: 1091173
> > Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
>
> Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
>
> > ---
> > Changes in v2:
> >   Move pointer dereference before pci_pool_free()
> >   Set pointer to NULL after free
> >
> >   drivers/usb/gadget/udc/pch_udc.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/gadget/udc/pch_udc.c
> > b/drivers/usb/gadget/udc/pch_udc.c
> > index a97da64..73bb58f 100644
> > --- a/drivers/usb/gadget/udc/pch_udc.c
> > +++ b/drivers/usb/gadget/udc/pch_udc.c
> > @@ -1522,8 +1522,9 @@ static void pch_udc_free_dma_chain(struct
> > pch_udc_dev *dev,
> >   		/* do not free first desc., will be done by free for request */
> >   		td = phys_to_virt(addr);
> >   		addr2 = (dma_addr_t)td->next;
> > -		pci_pool_free(dev->data_requests, td, addr);
> >   		td->next = 0x00;
>
> Or just drop this.  pci_pool_free doesnât care about contents of td.
> Itâs just a void* for it.
>
> > +		pci_pool_free(dev->data_requests, td, addr);
> > +		td = NULL;
>
> This isnât necessary either.  td will get overwritten on next iteration
> and once weâre done itâs not used again.
>
> >   		addr = addr2;
> >   	}
> >   	req->chain_len = 1;

Thanks for your comments, I will send version 3 shortly.
--
Gustavo A. R. Silva