linux-kernel - Re: [PATCH] net: Fix UAF in ieee80211_scan

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Message-ID: <1823a705ed0.2c95d162772051.7830246635749918178@siddh.me>
Date:   Tue, 26 Jul 2022 17:46:59 +0530
From:   Siddh Raman Pant <code@...dh.me>
To:     "Eric Dumazet" <edumazet@...gle.com>
Cc:     "Johannes Berg" <johannes@...solutions.net>,
        "David S . Miller" <davem@...emloft.net>,
        "Jakub Kicinski" <kuba@...nel.org>,
        "Paolo Abeni" <pabeni@...hat.com>,
        "linux-wireless" <linux-wireless@...r.kernel.org>,
        "netdev" <netdev@...r.kernel.org>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "linux-kernel-mentees" 
        <linux-kernel-mentees@...ts.linuxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH] net: Fix UAF in ieee80211_scan_rx()

On Tue, 26 Jul 2022 15:37:16 +0530  Eric Dumazet <edumazet@...gle.com> wrote:
> Note: this is slightly racy.
> 
> You are supposed to follow this order in this situation.
> 
> 1) Clear the pointer
> 
> Then:
> 
> 2) wait an rcu grace period (synchronize_rcu()) or use call_rcu()/kfree_rcu().
>  

Noted. Due to rcu_dereference() used to get scan_req, null ptr dereference
cannot happen. That had completely missed my eyes, sorry for that.

I will send a v2.

Thanks,
Siddh