linux-kernel - Re:Re: [PATCH] drm/panthor: Fix NULL pointer dereference on panthor_fw

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Message-ID: <4e8c1dcc.54f2.19bd4f4f1ae.Coremail.andyshrk@163.com>
Date: Mon, 19 Jan 2026 14:33:01 +0800 (CST)
From: "Andy Yan" <andyshrk@....com>
To: "Liviu Dudau" <liviu.dudau@....com>
Cc: "Karunika Choo" <karunika.choo@....com>, dri-devel@...ts.freedesktop.org,
	nd@....com, "Boris Brezillon" <boris.brezillon@...labora.com>,
	"Steven Price" <steven.price@....com>,
	"Maarten Lankhorst" <maarten.lankhorst@...ux.intel.com>,
	"Maxime Ripard" <mripard@...nel.org>,
	"Thomas Zimmermann" <tzimmermann@...e.de>,
	"David Airlie" <airlied@...il.com>,
	"Simona Vetter" <simona@...ll.ch>, linux-kernel@...r.kernel.org,
	aishwarya.tcv@....com
Subject: Re:Re: [PATCH] drm/panthor: Fix NULL pointer dereference on
 panthor_fw_unplug


Hello,

At 2025-12-16 20:51:53, "Liviu Dudau" <liviu.dudau@....com> wrote:
>On Mon, Dec 15, 2025 at 08:33:12PM +0000, Karunika Choo wrote:
>> This patch removes the MCU halt and wait for halt procedures during
>> panthor_fw_unplug() as the MCU can be in a variety of states or the FW
>> may not even be loaded/initialized at all, the latter of which can lead
>> to a NULL pointer dereference.
>> 
>> It should be safe on unplug to just disable the MCU without waiting for
>> it to halt as it may not be able to.
>> 
>> Fixes: 514072549865 ("drm/panthor: Support GLB_REQ.STATE field for Mali-G1 GPUs")
>> Suggested-by: Boris Brezillon <boris.brezillon@...labora.com>
>> Signed-off-by: Karunika Choo <karunika.choo@....com>
>
>Reviewed-by: Liviu Dudau <liviu@...au.co.uk>

  Tested-by: Andy Yan <andyshrk@....com>

Hope can be merged in 6.19 release cycle.


>
>Best regards,
>Liviu
>
>> ---
>>  drivers/gpu/drm/panthor/panthor_fw.c | 4 ----
>>  1 file changed, 4 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
>> index 4beaa589ba66..a64ec8756bed 100644
>> --- a/drivers/gpu/drm/panthor/panthor_fw.c
>> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
>> @@ -1261,10 +1261,6 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
>>  		if (ptdev->fw->irq.irq)
>>  			panthor_job_irq_suspend(&ptdev->fw->irq);
>>  
>> -		panthor_fw_halt_mcu(ptdev);
>> -		if (!panthor_fw_wait_mcu_halted(ptdev))
>> -			drm_warn(&ptdev->base, "Failed to halt MCU on unplug");
>> -
>>  		panthor_fw_stop(ptdev);
>>  	}
>>  
>> -- 
>> 2.49.0
>>