linux-kernel - Re: [PATCH] opp: Fix use-after-free in lazy_opp

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Date:   Tue, 30 May 2023 14:43:30 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Stephan Gerhold <stephan.gerhold@...nkonzept.com>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] opp: Fix use-after-free in lazy_opp_tables after probe
 deferral

On 30-05-23, 10:31, Stephan Gerhold wrote:
> Thanks, this seems to fix the crash as well. Are you going to handle it
> or should I send a v2 with this diff?

Please send a V2 :)

> During _allocate_opp_table() it's accessed without the opp_table_lock,
> because of
> 
> 	/* Drop the lock to reduce the size of critical section */
> 	mutex_unlock(&opp_table_lock);
> 
> 	if (opp_table) {
> 		/* ... */
> 		mutex_lock(&opp_table_lock);
> 	} else {
> 		opp_table = _allocate_opp_table(dev, index);
> 
> 		mutex_lock(&opp_table_lock);
> 		/* ... */
> 	}
> 
> This doesn't seem to cause any problems in my case though so it's
> unrelated to the crash I observed.

Hmm, right. Maybe we need a lock for that list, want to take that up ?

-- 
viresh