Re: [PATCH v2 1/4] media: imx8-isi: fix use-after-free on remove

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hello Xiaolei,

Thank you for the patch.

On Wed, May 06, 2026 at 11:12:07AM +0800, Xiaolei Wang wrote:
> KASAN reports a slab-use-after-free in __media_entity_remove_link()
> during rmmod of imx8_isi:
> 
>   BUG: KASAN: slab-use-after-free in __media_entity_remove_link+0x608/0x650
>   Read of size 2 at addr ffff0000d47cb02a by task rmmod/724
> 
>   Call trace:
>    __media_entity_remove_link+0x608/0x650
>    __media_entity_remove_links+0x78/0x144
>    __media_device_unregister_entity+0x150/0x280
>    media_device_unregister_entity+0x48/0x68
>    v4l2_device_unregister_subdev+0x158/0x300
>    v4l2_async_unbind_subdev_one+0x22c/0x358
>    v4l2_async_nf_unbind_all_subdevs+0xfc/0x1c0
>    v4l2_async_nf_unregister+0x5c/0x14c
>    mxc_isi_remove+0x124/0x2a0 [imx8_isi]
> 
>   Allocated by task 249:
>    __kmalloc_noprof+0x27c/0x690
>    mxc_isi_crossbar_init+0x22c/0x560 [imx8_isi]
> 
>   Freed by task 724:
>    kfree+0x1e4/0x5b0
>    mxc_isi_crossbar_cleanup+0x34/0x80 [imx8_isi]
>    mxc_isi_remove+0x11c/0x2a0 [imx8_isi]
> 
> The problem is that mxc_isi_remove() calls mxc_isi_crossbar_cleanup()
> before mxc_isi_v4l2_cleanup(). The crossbar cleanup frees the media
> entity pads, but the subsequent v4l2 cleanup still tries to remove
> media links that reference those pads.
> 
> Fix this by calling mxc_isi_v4l2_cleanup() before
> mxc_isi_crossbar_cleanup() to ensure all media entities are properly
> unregistered while the pads are still valid.
> 
> Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
> Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
> index 4bf8570e1b9e..2d639b789910 100644
> --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
> +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
> @@ -556,8 +556,8 @@ static void mxc_isi_remove(struct platform_device *pdev)
>  		mxc_isi_pipe_cleanup(pipe);
>  	}
>  
> -	mxc_isi_crossbar_cleanup(&isi->crossbar);
>  	mxc_isi_v4l2_cleanup(isi);
> +	mxc_isi_crossbar_cleanup(&isi->crossbar);
>  }
>  
>  static const struct of_device_id mxc_isi_of_match[] = {

-- 
Regards,

Laurent Pinchart