Re: [PATCH] wifi: mac80211: don't ask rate control with zero rate mask if scanning

From: Dmitry Antipov <dmantipov@yandex.ru>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Felix Fietkau <nbd@nbd.name>, Kalle Valo <kvalo@kernel.org>,
	linux-wireless@vger.kernel.org, lvc-project@linuxtesting.org,
	syzbot+fdc5123366fb9c3fdc6d@syzkaller.appspotmail.com
Subject: Re: [PATCH] wifi: mac80211: don't ask rate control with zero rate mask if scanning
Date: Wed, 24 Jan 2024 18:11:16 +0300	[thread overview]
Message-ID: <6499241c-8508-45de-816b-f36c1a202801@yandex.ru> (raw)
In-Reply-To: <58970b94a314414402a932576ec54188c0675016.camel@sipsolutions.net>

On 1/19/24 20:19, Johannes Berg wrote:

> I was trying to let you come up with a patch for learning, but I think
> at this point just making one illustrates better what I'm thinking ...
> Here's one, but I haven't even compiled this:

Hmm... this:

> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -701,7 +701,9 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
>   	txrc.bss_conf = &tx->sdata->vif.bss_conf;
>   	txrc.skb = tx->skb;
>   	txrc.reported_rate.idx = -1;
> -	txrc.rate_idx_mask = tx->sdata->rc_rateidx_mask[info->band];
> +
> +	if (!(info->control.flags & IEEE80211_TX_CTRL_SCAN_TX))
> +		txrc.rate_idx_mask = tx->sdata->rc_rateidx_mask[info->band];
>   
>   	if (tx->sdata->rc_has_mcs_mask[info->band])
>   		txrc.rate_idx_mcs_mask =

leaves 'rate_idx_mask' unset (i.e. zero) even for band 0 and then
causes the same WARN_ONCE() even earlier (before switching to band 1).

Dmitry