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Message-ID: <6c7765f13b715e67637438c6dffaa5a369758519.camel@sipsolutions.net>
Subject: Re: [PATCH] wifi: mac80211: sband's null check should precede params
From: Johannes Berg <johannes@sipsolutions.net>
To: Edward Adam Davis <eadavis@qq.com>, 
	syzbot+62d7eef57b09bfebcd84@syzkaller.appspotmail.com
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, 
 linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, 
 llvm@lists.linux.dev, nathan@kernel.org, ndesaulniers@google.com, 
 netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com,
  trix@redhat.com
Date: Wed, 29 Nov 2023 07:57:07 +0100
In-Reply-To: <tencent_0CCA1979CFA30DC8A5CF8DDC92365DCE5D07@qq.com>
References: <000000000000efc64705ff8286a1@google.com>
	 <tencent_0CCA1979CFA30DC8A5CF8DDC92365DCE5D07@qq.com>
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On Wed, 2023-11-29 at 13:48 +0800, Edward Adam Davis wrote:
>=20
> [Analysis]
> When ieee80211_get_link_sband() fails to find a valid sband and first che=
cks=20
> for params in sta_link_apply_parameters(), it will return 0 due to new_li=
nk=20
> being 0, which will lead to an incorrect process after sta_apply_paramete=
rs().
>=20
> [Fix]
> First obtain sband and perform a non null check before checking the param=
s.

Not sure I can even disagree with that analysis, it seems right, but ...

> +	if (!link || !link_sta)
> +		return -EINVAL;
> +
> +	sband =3D ieee80211_get_link_sband(link);
> +	if (!sband)
> +		return -EINVAL;
> +
>  	/*
>  	 * If there are no changes, then accept a link that doesn't exist,
>  	 * unless it's a new link.

There's a comment here which is clearly not true after this change,
since you've already returned for !link_sta?

johannes