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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Jia-Ju Bai <baijiaju1990@gmail.com>
Cc:     ath9k-devel@qca.qualcomm.com, davem@davemloft.net,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ath9k: Fix possible data races in ath_set_channel()
References: <20200111171528.7053-1-baijiaju1990@gmail.com>
Date:   Mon, 13 Jan 2020 09:17:28 +0200
In-Reply-To: <20200111171528.7053-1-baijiaju1990@gmail.com> (Jia-Ju Bai's
        message of "Sun, 12 Jan 2020 01:15:28 +0800")
Message-ID: <87a76rsu47.fsf@codeaurora.org>
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Jia-Ju Bai <baijiaju1990@gmail.com> writes:

> The functions ath9k_config() and ath_ani_calibrate() may be concurrently
> executed.
>
> A variable survey->filled is accessed with holding a spinlock
> common->cc_lock, through:
> ath_ani_calibrate()
>     spin_lock_irqsave(&common->cc_lock, flags);
>     ath_update_survey_stats()
>         ath_update_survey_nf()
>             survey->filled |= SURVEY_INFO_NOISE_DBM;
>
> The identical variables sc->cur_survey->filled and 
> sc->survey[pos].filled is accessed without holding this lock, through:
> ath9k_config()
>     ath_chanctx_set_channel()
>         ath_set_channel()
>             sc->cur_survey->filled &= ~SURVEY_INFO_IN_USE;
>             sc->cur_survey->filled |= SURVEY_INFO_IN_USE;
>             else if (!(sc->survey[pos].filled & SURVEY_INFO_IN_USE))
>             ath_update_survey_nf
>                 survey->filled |= SURVEY_INFO_NOISE_DBM;
>
> Thus, possible data races may occur.
>
> To fix these data races, in ath_set_channel(), these variables are
> accessed with holding the spinlock common->cc_lock.
>
> These data races are found by the runtime testing of our tool DILP-2.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>

I need a detailed review from somone familiar with ath9k before I can
consider applying this.

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