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From:   Kalle Valo <kvalo@kernel.org>
To:     Jiri Kosina <jikos@kernel.org>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ping-Ke Shih <pkshih@realtek.com>
Subject: Re: [PATCH] rtw89: fix RCU usage in rtw89_core_txq_push() (was Re: [PATCH] mac80211: fix RCU usage in ieee80211_tx_h_select_key())
References: <nycvar.YFH.7.76.2202151643220.11721@cbobk.fhfr.pm>
        <af6abf72593074c007fe42205e941dabfd08bf3a.camel@sipsolutions.net>
        <nycvar.YFH.7.76.2202151700540.11721@cbobk.fhfr.pm>
Date:   Tue, 15 Feb 2022 19:27:43 +0200
In-Reply-To: <nycvar.YFH.7.76.2202151700540.11721@cbobk.fhfr.pm> (Jiri
        Kosina's message of "Tue, 15 Feb 2022 17:11:11 +0100 (CET)")
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Jiri Kosina <jikos@kernel.org> writes:

> On Tue, 15 Feb 2022, Johannes Berg wrote:
>
>> > 
>> > 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?
>
> Right you are, thanks.
>
> CCing Ping-Ke Shih; find updated fix below.
>
>
>
>
> From: Jiri Kosina <jkosina@suse.cz>
> Subject: [PATCH] rtw89: fix RCU usage in rtw89_core_txq_push()
>
> ieee80211_tx_h_select_key() is performing a series of RCU dereferences,
> but rtw89_core_txq_push() is calling it (via ieee80211_tx_dequeue_ni())
> without RCU read-side lock held; fix that.

I think we have discussed this before, but patchwork can't handle
patches the way you embed them in email discussions:

https://patchwork.kernel.org/project/linux-wireless/patch/nycvar.YFH.7.76.2202151700540.11721@cbobk.fhfr.pm/

Please resubmit.

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