Received-SPF: softfail (google.com: domain of transitioning linux-wireless-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Message-ID: <af6abf72593074c007fe42205e941dabfd08bf3a.camel@sipsolutions.net>
Subject: Re: [PATCH] mac80211: fix RCU usage in ieee80211_tx_h_select_key()
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Jiri Kosina <jikos@kernel.org>
Cc:     linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 15 Feb 2022 16:50:33 +0100
In-Reply-To: <nycvar.YFH.7.76.2202151643220.11721@cbobk.fhfr.pm>
References: <nycvar.YFH.7.76.2202151643220.11721@cbobk.fhfr.pm>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.42.3 (3.42.3-1.fc35) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

> 
> ieee80211_tx_h_select_key() is performing a series of RCU dereferences, 
> but none of the callers seems to be taking RCU read-side lock; let's 
> acquire the lock in ieee80211_tx_h_select_key() itself.
> 
but but ...

>   ieee80211_tx_dequeue+0x1a7/0x1260 [mac80211 911c23e2351c0ae60b597a67b1204a5ea955e365]
>   rtw89_core_txq_work+0x1a6/0x420 [rtw89_core b39ba493f2e517ad75e0f8187ecc24edf58bbbea]

/**
 * ieee80211_tx_dequeue - dequeue a packet from a software tx queue
 *
 * @hw: pointer as obtained from ieee80211_alloc_hw()
 * @txq: pointer obtained from station or virtual interface, or from
 *      ieee80211_next_txq()
 *
 * Returns the skb if successful, %NULL if no frame was available.
 *
 * Note that this must be called in an rcu_read_lock() critical section,
 * which can only be released after the SKB was handled. Some pointers in
[...]

-> driver bug?

johannes