Subject: Re: [PATCH v3 2/2] drm/rockchip: dw_dp: Release core resources

From: Cristian Ciocaltea <[email-masked]>
Date: Mon, 1 Jun 2026 19:20:12 +0300

Hi Andy,

On 5/31/26 1:29 PM, Andy Yan wrote:
> Hello,
> 
> On 3/27/26 08:55, Cristian Ciocaltea wrote:
>> Core resources such as the DisplayPort AUX channel get initialized and
>> registered during dw_dp_bind(), but are never unregistered, which may
>> lead to memory leaks and/or use-after-free:
>>
>> [  224.661371] BUG: KASAN: slab-use-after-free in device_is_dependent+0xe0/0x2b0
>> [  224.662015] Read of size 8 at addr ffff00011aee8550 by task modprobe/658
>> [  224.662612]
>> [  224.662752] CPU: 7 UID: 0 PID: 658 Comm: modprobe Not tainted 7.0.0-rc2-next-20260305 #14 PREEMPT
>> [  224.662759] Hardware name: Radxa ROCK 5B (DT)
>> [  224.662762] Call trace:
>> [  224.662764]  show_stack+0x20/0x38 (C)
>> [  224.662772]  dump_stack_lvl+0x6c/0x98
>> [  224.662777]  print_report+0x160/0x4b8
>> [  224.662783]  kasan_report+0xb4/0xe0
>> [  224.662790]  __asan_report_load8_noabort+0x20/0x30
>> [  224.662796]  device_is_dependent+0xe0/0x2b0
>> [  224.662802]  device_is_dependent+0x108/0x2b0
>> [  224.662808]  device_link_add+0x1f8/0x10b0
>> [  224.662813]  devm_of_phy_get_by_index+0x120/0x200
>> [  224.662819]  dw_dp_bind+0x34c/0xb10 [dw_dp]
>> [  224.662830]  dw_dp_rockchip_bind+0x194/0x250 [rockchipdrm]
>> [  224.662864]  component_bind_all+0x3a8/0x720
>> [  224.662869]  rockchip_drm_bind+0x120/0x390 [rockchipdrm]
>> [  224.662899]  try_to_bring_up_aggregate_device+0x76c/0x838
>> [  224.662904]  component_master_add_with_match+0x1f4/0x230
>> [  224.662909]  rockchip_drm_platform_probe+0x420/0x538 [rockchipdrm]
>> [  224.662939]  platform_probe+0xe8/0x168
>> [  224.662945]  really_probe+0x340/0x828
>> [  224.662950]  __driver_probe_device+0x2e0/0x350
>> [  224.662954]  driver_probe_device+0x80/0x140
>> [  224.662959]  __driver_attach+0x398/0x460
>> [  224.662964]  bus_for_each_dev+0xe0/0x198
>> [  224.662968]  driver_attach+0x50/0x68
>> [  224.662972]  bus_add_driver+0x2a0/0x4c0
>> [  224.662977]  driver_register+0x294/0x360
>> [  224.662982]  __platform_driver_register+0x7c/0x98
>> [  224.662987]  rockchip_drm_init+0xc4/0xff8 [rockchipdrm]
>>
>> Since a previous commit exported dw_dp_unbind() function in DW DP core
>> library to take care of the necessary cleanup, use this in the
>> component's unbind() callback, as well as in its bind() error path.
>>
>> Fixes: d68ba7bac955 ("drm/rockchip: Add RK3588 DPTX output support")
>> Signed-off-by: Cristian Ciocaltea <[email-masked]>
>> ---
>>   drivers/gpu/drm/rockchip/dw_dp-rockchip.c | 20 +++++++++++++++++---
>>   1 file changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
>> index 22c0911f1896..8cba90d2dd56 100644
>> --- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
>> +++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
>> @@ -108,14 +108,28 @@ static int dw_dp_rockchip_bind(struct device *dev, struct device *master, void *
>>         connector = drm_bridge_connector_init(drm_dev, encoder);
>>       if (IS_ERR(connector))
>> -        return dev_err_probe(dev, PTR_ERR(connector),
>> -                     "Failed to init bridge connector");
>> +        ret = dev_err_probe(dev, PTR_ERR(connector),
>> +                    "Failed to init bridge connector");
>> +    else
>> +        ret = drm_connector_attach_encoder(connector, encoder);
>>   -    return drm_connector_attach_encoder(connector, encoder);
> 
> This line has already been removed in the latest code.

Indeed, handled now in v4 [1] by rebasing onto latest drm-misc. 
Also added a new patch to fix a missing "\n".

Thanks for reviewing!

Regards,
Cristian

[1] https://lore.kernel.org/all/[email-masked]/