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From:   Koen Vandeputte <koen.vandeputte@citymesh.com>
Date:   Wed, 12 Jul 2023 11:05:00 +0200
Message-ID: <CAPh3n82BY0bFkHs6DKKf6+ZUZw+DJmTy7=JEG8REFHyHFMqoVQ@mail.gmail.com>
Subject: Re: [PATCH] wifi: nl80211: fix mbssid nesting
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org, John Crispin <john@phrozen.org>,
        Aloka Dixit <alokad@codeaurora.org>, stable@vger.kernel.org
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On Wed, Jul 12, 2023 at 10:44=E2=80=AFAM Johannes Berg
<johannes@sipsolutions.net> wrote:
>
> On Wed, 2023-07-12 at 10:38 +0200, Koen Vandeputte wrote:
> > Executing command NL80211_CMD_GET_WIPHY and parsing it's output
> > natively without libnl shows following attributes as part of
> > the nl80211 generated netlink message (part 16):
> >
> > GetWiphy: Type: 1
> > GetWiphy: Type: 2
> > GetWiphy: Type: 46
> > GetWiphy: Type: 33074 <-- wrong enum value, above MAX also ..
>
> That's not wrong, that's just NLA_F_NESTED | NL80211_ATTR_MBSSID_CONFIG,
> since it *is* in fact a nested attribute.

ahha! so one should check on each received attribute if this flag is set?

>
> > Switching to nla_nest_start_noflag() which ommits the NLA_F_NESTED
> > flag (like most other similar functions do) fixes this:
> >
> > GetWiphy: Type: 1
> > GetWiphy: Type: 2
> > GetWiphy: Type: 46
> > GetWiphy: Type: 306 <-- correct enum value
> > GetWiphy: Type: 316
>
> Let's say it _changes_ it, but it doesn't _fix_ it, since it's not
> broken.
noted
>
> Using nla_nest_start_noflag() is a legacy thing, it shouldn't be done
> any more. You need to update your userspace, I'm not applying this
> patch.

Sure, no problem.
I guess all the ones with the noflag so far are using it to avoid
breaking legacy stuff?

>
> johannes
>

Thanks for the quick review.
Highly appreciated!