2022-04-24 21:50:44

by Pavel Skripkin

Subject: Re: [PATCH 2/3] staging: r8188eu: fix null check in _rtw_enqueue_recvframe

Hi Vihas,

On 4/24/22 19:31, Vihas Makwana wrote:
> There's a NULL check on padapter in rtw_recv.c:189 which makes no sense as
> rtw_recv.c:184 dereferences it unconditionally and it would have already
> crashed at this point.
> Fix this by moving the dereference line inside the check.
>
> Signed-off-by: Vihas Makwana <[email protected]>
> ---
> drivers/staging/r8188eu/core/rtw_recv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/r8188eu/core/rtw_recv.c b/drivers/staging/r8188eu/core/rtw_recv.c
> index 4cf9b4b8f..7d306a3c6 100644
> --- a/drivers/staging/r8188eu/core/rtw_recv.c
> +++ b/drivers/staging/r8188eu/core/rtw_recv.c
> @@ -181,12 +181,13 @@ int rtw_free_recvframe(struct recv_frame *precvframe, struct __queue *pfree_recv
> int _rtw_enqueue_recvframe(struct recv_frame *precvframe, struct __queue *queue)
> {
> struct adapter *padapter = precvframe->adapter;
> - struct recv_priv *precvpriv = &padapter->recvpriv;
> + struct recv_priv *precvpriv;

Actually, `&padapter->recvpriv` is not a de-reference, it's just address
calculation, so in case of padapder being NULL precvpriv will contain
offsetof(struct adapter, recvpriv).

>
> list_del_init(&precvframe->list);
> list_add_tail(&precvframe->list, get_list_head(queue));
>
> if (padapter) {
> + precvpriv = &padapter->recvpriv;
> if (queue == &precvpriv->free_recv_queue)
> precvpriv->free_recvframe_cnt++;
> }




With regards,
Pavel Skripkin

2022-04-25 20:07:15

by Vihas Makwana

Subject: Re: [PATCH 2/3] staging: r8188eu: fix null check in _rtw_enqueue_recvframe

On Mon, Apr 25, 2022 at 12:23 AM Pavel Skripkin <[email protected]> wrote:
>
> Hi Vihas,
>
> On 4/24/22 19:31, Vihas Makwana wrote:
> > There's a NULL check on padapter in rtw_recv.c:189 which makes no sense as
> > rtw_recv.c:184 dereferences it unconditionally and it would have already
> > crashed at this point.
> > Fix this by moving the dereference line inside the check.
> >
> > Signed-off-by: Vihas Makwana <[email protected]>
> > ---
> > drivers/staging/r8188eu/core/rtw_recv.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/r8188eu/core/rtw_recv.c b/drivers/staging/r8188eu/core/rtw_recv.c
> > index 4cf9b4b8f..7d306a3c6 100644
> > --- a/drivers/staging/r8188eu/core/rtw_recv.c
> > +++ b/drivers/staging/r8188eu/core/rtw_recv.c
> > @@ -181,12 +181,13 @@ int rtw_free_recvframe(struct recv_frame *precvframe, struct __queue *pfree_recv
> > int _rtw_enqueue_recvframe(struct recv_frame *precvframe, struct __queue *queue)
> > {
> > struct adapter *padapter = precvframe->adapter;
> > - struct recv_priv *precvpriv = &padapter->recvpriv;
> > + struct recv_priv *precvpriv;
>
> Actually, `&padapter->recvpriv` is not a de-reference, it's just address
> calculation, so in case of padapder being NULL precvpriv will contain
> offsetof(struct adapter, recvpriv).
>
Oh, I see.
> >
> > list_del_init(&precvframe->list);
> > list_add_tail(&precvframe->list, get_list_head(queue));
> >
> > if (padapter) {
> > + precvpriv = &padapter->recvpriv;
> > if (queue == &precvpriv->free_recv_queue)
> > precvpriv->free_recvframe_cnt++;
> > }
>
>
>
>
> With regards,
> Pavel Skripkin



--
Thanks,
Vihas