CVE-2026-43169

In the Linux kernel, the following vulnerability has been resolved:

drm/buddy: Prevent BUG_ON by validating rounded allocation

When DRM_BUDDY_CONTIGUOUS_ALLOCATION is set, the requested size is

rounded up to the next power-of-two via roundup_pow_of_two().

Similarly, for non-contiguous allocations with large min_block_size,

the size is aligned up via round_up(). Both operations can produce a

rounded size that exceeds mm->size, which later triggers

BUG_ON(order > mm->max_order).

Example scenarios:

- 9G CONTIGUOUS allocation on 10G VRAM memory:

roundup_pow_of_two(9G) = 16G > 10G

- 9G allocation with 8G min_block_size on 10G VRAM memory:

round_up(9G, 8G) = 16G > 10G

Fix this by checking the rounded size against mm->size. For

non-contiguous or range allocations where size > mm->size is invalid,

return -EINVAL immediately. For contiguous allocations without range

restrictions, allow the request to fall through to the existing

__alloc_contig_try_harder() fallback.

This ensures invalid user input returns an error or uses the fallback

path instead of hitting BUG_ON.

v2: (Matt A)

- Add Fixes, Cc stable, and Closes tags for context