Re: [PATCH] drm/panthor: reject zero-sized firmware sections

[Steven Price <steven.price@arm.com>]

On 20/07/2026 12:30, Osama Abdelkader wrote:
> panthor_fw_load_section_entry() skips BO creation when the firmware section
> VA range is empty. The section is still added to the firmware section list,
> leaving section->mem as NULL.
> 
> Later reload and unplug paths iterate over all firmware sections and
> dereference section->mem, which can lead to a NULL pointer dereference.

Good catch.

> Reject zero-sized firmware sections before adding them to the section list.

Sadly we were trying to support zero-sized sections - hence the "if
(section_size)" further down.

I think it would probably be better to just not add the section to the
list if it's zero sized and otherwise accept the firmware.

Thanks,
Steve

> Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> Cc: stable@vger.kernel.org
> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
> ---
>  drivers/gpu/drm/panthor/panthor_fw.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index a338c4f0a7f5..6335893d3f16 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -596,6 +596,11 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
>  	}
>  
>  	section_size = hdr.va.end - hdr.va.start;
> +	if (!section_size) {
> +		drm_err(&ptdev->base, "Firmware corrupted, zero-sized section\n");
> +		return -EINVAL;
> +	}
> +
>  	data_size = hdr.data.end - hdr.data.start;
>  	if (data_size > section_size) {
>  		drm_err(&ptdev->base, "Firmware corrupted, section data exceeds section size\n");