Allocation of Resources Without Limits or Throttling Affecting kernel-rt-64k-core package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.14% (5th percentile)

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  • Snyk IDSNYK-RHEL10-KERNELRT64KCORE-18745083
  • published13 Aug 2026
  • disclosed12 Aug 2026

Introduced: 12 Aug 2026

NewCVE-2026-68436  (opens in a new tab)
CWE-770  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:10 kernel-rt-64k-core.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-core package and not the kernel-rt-64k-core package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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

drm/amd/display: use kvzalloc to allocate struct dc

struct dc has grown large over time (most of it the two inlined dc_scratch_space copies) and now sits close to the page allocator's 4 MiB contiguous allocation limit. Its actual size is not fixed by the source alone, it also depends on the compiler and the .config, so it can easily cross 4 MiB, e.g. with a newer GCC or a config change.

dc_create() allocates it with kzalloc(). Once struct dc exceeds 4 MiB the request is rounded up to order 11 (8 MiB), which is above MAX_PAGE_ORDER, so the page allocator warns and returns NULL. dc_create() then fails, DM init fails and amdgpu probe aborts with -EINVAL:

WARNING: mm/page_alloc.c:5197 at __alloc_frozen_pages_noprof+0x2f9/0x380 dc_create+0x38/0x660 [amdgpu] amdgpu_dm_init+0x2d9/0x510 [amdgpu] dm_hw_init+0x1b/0x90 [amdgpu] amdgpu_device_init.cold+0x150d/0x1e13 [amdgpu] amdgpu_driver_load_kms+0x19/0x80 [amdgpu] amdgpu_pci_probe+0x1e2/0x4c0 [amdgpu]

dc_create() then returns NULL and DM init fails, which aborts the whole GPU init and makes amdgpu probe fail with -EINVAL ("hw_init of IP block <dm> failed -22"), leaving the display unusable. The subsequent amdgpu_irq_put() warnings during teardown are just fallout of unwinding a half-initialized device.

struct dc is a software-only bookkeeping structure that is never handed to hardware DMA and is only ever kept as an opaque pointer, so it does not require physically contiguous memory. Allocate it with kvzalloc() (and free it with kvfree()) so that the allocator can fall back to vmalloc() when a contiguous allocation of that size is not available, which also avoids the MAX_PAGE_ORDER warning entirely.

v2:

  • Rebase to amd-staging-drm-next.

(cherry picked from commit 991e0516a8072f2292681c6ae98a924ab0e32575)

CVSS Base Scores

version 3.1