linux-kernel - Re: [PATCH v2] drm/of: free the iterator object on failure

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Message-ID: <f723a5e0-5b9a-c807-f51d-9acc57058a80@arm.com>
Date:   Thu, 15 Jul 2021 11:32:50 +0100
From:   Steven Price <steven.price@....com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Biju Das <biju.das.jz@...renesas.com>,
        Pavel Machek <pavel@...x.de>
Subject: Re: [PATCH v2] drm/of: free the iterator object on failure

On 14/07/2021 16:26, Laurent Pinchart wrote:
> Hi Steven,
> 
> Thank you for the patch.
> 
> On Wed, Jul 14, 2021 at 03:33:00PM +0100, Steven Price wrote:
>> When bailing out due to the sanity check the iterator value needs to be
>> freed because the early return prevents for_each_child_of_node() from
>> doing the dereference itself.
>>
>> Fixes: 6529007522de ("drm: of: Add drm_of_lvds_get_dual_link_pixel_order")
>> Signed-off-by: Steven Price <steven.price@....com>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

Thanks! Applied to drm-misc-next.

Steve

>> ---
>>  drivers/gpu/drm/drm_of.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> v2: Fixes now refers to the original commit as suggested by Laurent, rather
>> than 4ee48cc5586b ("drm: of: Fix double-free bug") which only fixed part of
>> the problem. Note that 4ee48cc5586b is a dependency for this patch to
>> cleanly apply.
>>
>> diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
>> index 197c57477344..997b8827fed2 100644
>> --- a/drivers/gpu/drm/drm_of.c
>> +++ b/drivers/gpu/drm/drm_of.c
>> @@ -331,8 +331,10 @@ static int drm_of_lvds_get_remote_pixels_type(
>>  		 * configurations by passing the endpoints explicitly to
>>  		 * drm_of_lvds_get_dual_link_pixel_order().
>>  		 */
>> -		if (!current_pt || pixels_type != current_pt)
>> +		if (!current_pt || pixels_type != current_pt) {
>> +			of_node_put(endpoint);
>>  			return -EINVAL;
>> +		}
>>  	}
>>  
>>  	return pixels_type;
>