linux-kernel - Re: [PATCH V2] rtc: snvs: fix possible race condition

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Date:   Fri, 19 Jul 2019 09:33:16 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Anson.Huang@....com
Cc:     a.zummo@...ertech.it, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Linux-imx@....com
Subject: Re: [PATCH V2] rtc: snvs: fix possible race condition

On 19/07/2019 11:01:02+0800, Anson.Huang@....com wrote:
> From: Anson Huang <Anson.Huang@....com>
> 
> The RTC IRQ is requested before the struct rtc_device is allocated,
> this may lead to a NULL pointer dereference in IRQ handler.
> 
> To fix this issue, allocating the rtc_device struct and register rtc
> device before requesting the RTC IRQ.
> 
> Using devm_rtc_allocate_device/rtc_register_device instead of
> devm_rtc_device_register.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> ---
> Changes since V1:
> 	- move devm_request_irq() to after rtc device register done, make sure everything
> 	  is ready before enabling IRQ.

This opens another race condition, the first version of the patch was
correct.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com