Re: [PATCH] wifi: mac80211_hwsim: handle 5/10 MHz chanctx in rc update

[Lachlan Hodges]

Hi,

> The STA bandwidth enum has no sub-20 MHz states, so a normal 20 MHz link 
> STA falsely trips the warning on 5/10 MHz OCB channel contexts.so 
> a normal 20 MHz link STA falsely trips the warning on 5/10 MHz OCB 
> channel contexts.

There is also S1G widths :) but that doesn't really matter.

> Treat sub-20 MHz channel contexts as 20 MHz for this validation and use 
> the actual channel-context width in the warning message.
> 
> Fixes: aea9a6088ae46 ("wifi: mac80211_hwsim: do rc update per link")
> Reported-by: syzbot+c0472dd80bb8f668625f@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=c0472dd80bb8f668625f
> Signed-off-by: meihaipeng <meihaipeng@xxxxxxxxxxxxx>

Looking at the stack trace of this report and a few of the others,
it comes from mac80211_hwsim_sta_add() which calls the rc_update on
the new STA, so it would probably be better to do something similar
to what we did for S1G [1] since I'm pretty sure the rc_update()
path isn't reachable on 5/10MHz (just like S1G).

Though there are also quite a few 5/10MHz syzbot reports for various
things similar so maybe it's not worth it.. but that is up to
Johannes :).

[1] https://lore.kernel.org/linux-wireless/20260527033828.183821-2-lachlan.hodges@xxxxxxxxxxxxxx/

lachlan