Re: [PATCH 3/5] staging: r8188eu: use helper to check for broadcast address

Martin Kaiser
2021-10-22T09:21:21Z

Thus wrote Michael Straube (straube.linux@gmail.com):

> > > + !is_broadcast_ether_addr(GetAddr1Ptr(pframe)))

> Hi Martin,

> I'm not an expert regarding alignment. Is GetAddr1Ptr(pframe) always
> __aligned(2) as required by is_broadcast_ether_addr?

Hi Michael,

thanks for spotting this. To be honest, I didn't look at this in much
detail when I wrote the patch.

I suppose the pframe comes from recvbuf2recvframe().
precvframe = rtw_alloc_recvframe(pfree_recv_queue);
with
struct __queue *pfree_recv_queue = &precvpriv->free_recv_queue;

This should be initialised in _rtw_init_recv_priv().
rtw_init_queue(&precvpriv->free_recv_queue);
...
precvpriv->precv_frame_buf = (u8 *)N_BYTE_ALIGMENT((size_t)(precvpriv->pallocated_frame_buf), RXFRAME_ALIGN_SZ);
precvframe = (struct recv_frame *)precvpriv->precv_frame_buf;
and the frames are added to the free_recv_queue.
RXFRAME_ALIGN_SZ is 1<<8.

So pframe should be 256-byte aligned.
GetAddr1Ptr adds 4 to the start of pframe.

I guess we're safe here.

> > > @@ -841,7 +840,7 @@ void odm_RSSIMonitorCheck(struct odm_dm_struct *pDM_Odm)
> > > psta = pDM_Odm->pODM_StaInfo[i];
> > > if (IS_STA_VALID(psta) &&
> > > (psta->state & WIFI_ASOC_STATE) &&
> > > - memcmp(psta->hwaddr, bcast_addr, ETH_ALEN) &&
> > > + !is_broadcast_ether_addr(psta->hwaddr) &&

> Perhaps we should add __aligned(2) to the hwaddr variable in struct
> sta_info to be safe?

> u8 hwaddr[ETH_ALEN] __aligned(2);

Hmm, some of those arrays in other parts of the kernel have
__aligned(2), others don't...

Can anyone else give some guidance?

Thanks,
Martin