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Subject: Re: [PATCH 1/2] mac80211: handle lack of sband->bitrates in rates
To:     Thomas Pedersen <thomas@adapt-ip.com>,
        Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>
References: <20201002175308.16374-1-thomas@adapt-ip.com>
From:   Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
Message-ID: <f8d1c99d-f678-309a-80fb-0f886d1531c8@candelatech.com>
Date:   Fri, 2 Oct 2020 11:55:52 -0700
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On 10/2/20 10:53 AM, Thomas Pedersen wrote:
> Even though a driver or mac80211 shouldn't produce a
> legacy bitrate if sband->bitrates doesn't exist, don't
> crash if that is the case either.
> 
> This fixes a kernel panic if station dump is run before
> last_rate can be updated with a data frame when
> sband->bitrates is missing (eg. in S1G bands).
> 
> Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
> ---
>   net/mac80211/cfg.c      | 3 ++-
>   net/mac80211/sta_info.c | 4 ++++
>   2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
> index da70f174d629..e40160114824 100644
> --- a/net/mac80211/cfg.c
> +++ b/net/mac80211/cfg.c
> @@ -709,7 +709,8 @@ void sta_set_rate_info_tx(struct sta_info *sta,
>   		u16 brate;
>   
>   		sband = ieee80211_get_sband(sta->sdata);
> -		if (sband) {
> +		WARN_ON(sband && !sband->bitrates);

Maybe WARN_ON_ONCE to keep the spam down in case this is hit repeatedly
for some reason?

Same below...

Thanks,
Ben

> +		if (sband && sband->bitrates) {
>   			brate = sband->bitrates[rate->idx].bitrate;
>   			rinfo->legacy = DIV_ROUND_UP(brate, 1 << shift);
>   		}
> diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
> index f2840d1d95cf..0efb66b8f185 100644
> --- a/net/mac80211/sta_info.c
> +++ b/net/mac80211/sta_info.c
> @@ -2122,6 +2122,10 @@ static void sta_stats_decode_rate(struct ieee80211_local *local, u32 rate,
>   		int rate_idx = STA_STATS_GET(LEGACY_IDX, rate);
>   
>   		sband = local->hw.wiphy->bands[band];
> +
> +		if (WARN_ON(!sband->bitrates))
> +			break;
> +
>   		brate = sband->bitrates[rate_idx].bitrate;
>   		if (rinfo->bw == RATE_INFO_BW_5)
>   			shift = 2;
> 


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com