Re: [PATCH v2 2/2] drm/udl: clean up USB resources if drm_dev_register() fails

[Thomas Zimmermann <tzimmermann@suse.de>]

Am 24.09.26 um 08:44 schrieb Hui Peng:
> In udl_usb_probe(), udl_driver_create() calls udl_init(udl), which
> allocates USB URBs and DMA buffers via udl_alloc_urb_list() that are
> normally freed by udl_drop_usb() in udl_usb_disconnect(). If
> drm_dev_register() fails in udl_usb_probe(), udl_usb_probe() returns
> without calling udl_drop_usb(udl), leaking the allocated URB list and DMA
> buffers because udl_usb_disconnect() is not called when probe fails.
>
> Call udl_drop_usb(udl) when drm_dev_register() fails in udl_usb_probe().
>
> Tested in QEMU against Linux 7.3.0-rc3 using dummy_hcd by simulating
> a registration error in drm_dev_register(): on the unfixed kernel,
> udl_usb_probe() returned an error without calling udl_drop_usb(udl),
> leaking 8 allocated URBs and DMA buffers; whereas with this fix applied,
> udl_drop_usb(udl) is called on error, freeing all URB and DMA
> allocations.
>
> Fixes: 5320918b9a87 ("drm/udl: initial UDL driver (v4)")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM
> Signed-off-by: Hui Peng <benquike@gmail.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
> Changes in v2:
> - Split out as patch 2/2 as requested by Jani Nikula.
> - Added testing details in QEMU on drm_dev_register() failure cleanup.
>
>   drivers/gpu/drm/udl/udl_drv.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
> index 1922988625eb..239a6983f49f 100644
> --- a/drivers/gpu/drm/udl/udl_drv.c
> +++ b/drivers/gpu/drm/udl/udl_drv.c
> @@ -97,8 +97,10 @@ static int udl_usb_probe(struct usb_interface *interface,
>   		return PTR_ERR(udl);
>   
>   	r = drm_dev_register(&udl->drm, 0);
> -	if (r)
> +	if (r) {
> +		udl_drop_usb(udl);
>   		return r;
> +	}
>   
>   	DRM_INFO("Initialized udl on minor %d\n", udl->drm.primary->index);
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)