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SubjectRe: [PATCH 2/3] drm/ingenic: Register devm action to cleanup encoders
Hi Laurent,

Le lun. 18 janv. 2021 à 11:43, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> a écrit :
> Hi Paul,
>
> Thank you for the patch.
>
> On Sun, Jan 17, 2021 at 11:26:45AM +0000, Paul Cercueil wrote:
>> Since the encoders have been devm-allocated, they will be freed way
>> before drm_mode_config_cleanup() is called. To avoid use-after-free
>> conditions, we then must ensure that drm_encoder_cleanup() is called
>> before the encoders are freed.
>
> How about allocating the encoder with drmm_encoder_alloc() instead ?

That would work, but it is not yet in drm-misc-fixes :(

-Paul

>> Fixes: c369cb27c267 ("drm/ingenic: Support multiple panels/bridges")
>> Cc: <stable@vger.kernel.org> # 5.8+
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>> ---
>> drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>> index 368bfef8b340..d23a3292a0e0 100644
>> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
>> @@ -803,6 +803,11 @@ static void __maybe_unused
>> ingenic_drm_release_rmem(void *d)
>> of_reserved_mem_device_release(d);
>> }
>>
>> +static void ingenic_drm_encoder_cleanup(void *encoder)
>> +{
>> + drm_encoder_cleanup(encoder);
>> +}
>> +
>> static int ingenic_drm_bind(struct device *dev, bool
>> has_components)
>> {
>> struct platform_device *pdev = to_platform_device(dev);
>> @@ -1011,6 +1016,11 @@ static int ingenic_drm_bind(struct device
>> *dev, bool has_components)
>> return ret;
>> }
>>
>> + ret = devm_add_action_or_reset(dev, ingenic_drm_encoder_cleanup,
>> + encoder);
>> + if (ret)
>> + return ret;
>> +
>> ret = drm_bridge_attach(encoder, bridge, NULL, 0);
>> if (ret) {
>> dev_err(dev, "Unable to attach bridge\n");
>
> --
> Regards,
>
> Laurent Pinchart


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