linux-kernel - Re: [PATCH] counter: 104-quad-8: Fix race getting function mode and direction

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Date:   Sat, 22 Oct 2022 11:11:57 -0400
From:   William Breathitt Gray <wbg@...nel.org>
To:     William Breathitt Gray <william.gray@...aro.org>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] counter: 104-quad-8: Fix race getting function mode and
 direction

On Thu, Oct 20, 2022 at 10:11:21AM -0400, William Breathitt Gray wrote:
> The quad8_action_read() function checks the Count function mode and
> Count direction without first acquiring a lock. This is a race condition
> because the function mode could change by the time the direction is
> checked.
> 
> Because the quad8_function_read() already acquires a lock internally,
> the quad8_function_read() is refactored to spin out the no-lock code to
> a new quad8_function_get() function.
> 
> To resolve the race condition in quad8_action_read(), a lock is acquired
> before calling quad8_function_get() and quad8_direction_read() in order
> to get both function mode and direction atomically.
> 
> Fixes: f1d8a071d45b ("counter: 104-quad-8: Add Generic Counter interface support")
> Cc: stable@...r.kernel.org
> Signed-off-by: William Breathitt Gray <william.gray@...aro.org>

Queued for counter-fixes.

William Breathitt Gray

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