Re: [PATCH] drm/i915: Fix potential overflow of shmem scatterlist length

[Andi Shyti <andi.shyti@kernel.org>]

Hi Janusz,

...

> @@ -153,8 +153,12 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
>  			}
>  		} while (1);
>  

Perhaps we could add here:

	max_pages = max_segment >> PAGE_SHIFT;
	/* Just to be paranoic, but not necessary */
	if (!max_pages)
		max_pages = 1;


> -		nr_pages = min_t(unsigned long,
> -				folio_nr_pages(folio), page_count - i);
> +		nr_pages = min_array(((unsigned long[]) {
> +					folio_nr_pages(folio),
> +					page_count - i,
> +					max_segment / PAGE_SIZE,

max_segment >> PAGE_SHIFT ?

For clarity this can be written as

		nr_pages = min_t(unsigned long,
				folio_nr_pages(folio), page_count - i);
		nr_pages = min_t(unsigned long, nr_pages, max_pages);

But these are nitpicks, it's then up to you to choose the style.

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>

Thanks,
Andi

> +				      }), 3);
> +