Re: [PATCH 3/3] staging: r8188eu: fix null check in _rtw_free_mlme_priv

Pavel Skripkin
2022-04-24T19:00:21Z

Hi Vihas,

On 4/24/22 19:31, Vihas Makwana wrote:
> There's a NULL check on pmlmepriv in rtw_mlme.c:112 which makes no sense
> as rtw_free_mlme_priv_ie_data() dereferences it unconditionally and it
> would have already crashed at this point.
> Fix this by moving rtw_free_mlme_priv_ie_data() inside the check.
>
> Signed-off-by: Vihas Makwana <makvihas@gmail.com>

That's good catch, but looks like the check is just redundant

This function is called only from it's wrapper called
rtw_free_mlme_priv() and rtw_free_mlme_priv() is called from 2 places:

4 drivers/staging/r8188eu/os_dep/os_intfs.c|531 col 2|
rtw_free_mlme_priv(&padapter->mlmepriv);
5 drivers/staging/r8188eu/os_dep/os_intfs.c|579 col 2|
rtw_free_mlme_priv(&padapter->mlmepriv);

_Very_ unlikely that `&padapter->mlmepriv` expression will become NULL.

> ---
> drivers/staging/r8188eu/core/rtw_mlme.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
> index 081c02417..87c754462 100644
> --- a/drivers/staging/r8188eu/core/rtw_mlme.c
> +++ b/drivers/staging/r8188eu/core/rtw_mlme.c
> @@ -109,12 +109,10 @@ void rtw_free_mlme_priv_ie_data(struct mlme_priv *pmlmepriv)
>
> void _rtw_free_mlme_priv(struct mlme_priv *pmlmepriv)
> {
> -
> - rtw_free_mlme_priv_ie_data(pmlmepriv);
> -
> - if (pmlmepriv)
> + if (pmlmepriv) {
> + rtw_free_mlme_priv_ie_data(pmlmepriv);
> vfree(pmlmepriv->free_bss_buf);
> -
> + }
> }
>
> struct wlan_network *_rtw_alloc_network(struct mlme_priv *pmlmepriv)/* _queue *free_queue) */

With regards,
Pavel Skripkin