linux-kernel - Re: [PATCH] iio: accel: fxls8962af: Fix use after free in fxls8962af_fifo

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Message-ID: <67c33f11-0196-44f4-9cdd-762618cb88be@baylibre.com>
Date: Thu, 29 May 2025 13:49:16 -0500
From: David Lechner <dlechner@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Sean Nyekjaer <sean@...nix.com>, Jonathan Cameron <jic23@...nel.org>,
 Nuno Sá <nuno.sa@...log.com>,
 Andy Shevchenko <andy@...nel.org>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] iio: accel: fxls8962af: Fix use after free in
 fxls8962af_fifo_flush

On 5/29/25 1:16 PM, Andy Shevchenko wrote:
> On Thu, May 29, 2025 at 7:02 PM David Lechner <dlechner@...libre.com> wrote:
>> On 5/24/25 5:34 AM, Sean Nyekjaer wrote:
> 
> ...
> 
>> fxls8962af_suspend() calls enable_irq_wake(data->irq); before disabling the
>> interrupt by calling fxls8962af_buffer_predisable(indio_dev);
>>
>> It seems like the order should be reversed.
> 
> AFAIU the wake capability of IRQ line is orthogonal to the interrupt
> controller enabling (unmasking) / disabling (masking) the line itself.
> Or did you mean something else?
> 

I don't know enough about how suspend/wake stuff works to say for sure.

I just saw the comment:

	/*
	 * Disable buffer, as the buffer is so small the device will wake
	 * almost immediately.
	 */

so I assumed someone had observed something like this happening already.
If an interrupt occurs between enable_irq_wake() and actually
going into a low power mode, what effect does it have? I ask because I
don't know.