---
id: CVE-2026-98142
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/cirrus-qemu: Validate BAR0 size during probe

  The `cirrus-qemu` driver relies on `CIRRUS_VRAM_SIZE` (4 MB) to validate
  framebuffer sizes
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/cirrus-qemu: Validate BAR0 size during probe

  The `cirrus-qemu` driver relies on `CIRRUS_VRAM_SIZE` (4 MB) to validate
  framebuffer sizes. However, during PCI probe,…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 <
    0b5084a1f070ad1fc34e11945644ae034bbc774c
  - >-
    Linux >= ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 <
    26bd90c886218f36c9adeab206b0e27b4384e2f6
  - >-
    Linux >= ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 <
    144f51cd0ccc3ad47a6099917b7bb535611fb18f
  - >-
    Linux >= ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 <
    92312d333bf700798f92f30406c721bce87506f3
  - Linux 5.2
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:45.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98142'
references:
  - url: 'https://git.kernel.org/stable/c/0b5084a1f070ad1fc34e11945644ae034bbc774c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/144f51cd0ccc3ad47a6099917b7bb535611fb18f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/26bd90c886218f36c9adeab206b0e27b4384e2f6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/92312d333bf700798f92f30406c721bce87506f3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.809Z'
---

## Overview

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

drm/cirrus-qemu: Validate BAR0 size during probe

The `cirrus-qemu` driver relies on `CIRRUS_VRAM_SIZE` (4 MB) to validate
framebuffer sizes. However, during PCI probe, the driver mapped BAR0
without verifying that its size matches `CIRRUS_VRAM_SIZE`.

If a PCI device with a BAR0 smaller than 4 MB is bound to the driver, the
mapped VRAM will be smaller than expected. Because validation checks assume
4 MB VRAM, framebuffers larger than the mapped memory can be created.

When the display plane is updated (e.g. during release),
`cirrus_primary_plane_helper_atomic_update()` copies the framebuffer to
VRAM using `drm_fb_memcpy()`. Writing past the end of the mapped I/O memory
causes a supervisor write page fault:

BUG: unable to handle page fault for address: ffffc9000389c000
...
RIP: 0010:memcpy_toio+0x7c/0xe0 arch/x86/lib/iomem.c:110
...
Call Trace:
 <TASK>
 iosys_map_memcpy_to include/linux/iosys-map.h:285 [inline]
 drm_fb_memcpy+0x325/0x5d0 drivers/gpu/drm/drm_format_helper.c:442
 cirrus_primary_plane_helper_atomic_update+0x98a/0xb00
 drivers/gpu/drm/tiny/cirrus-qemu.c:358
 drm_atomic_helper_commit_planes+0x626/0xea0
 drivers/gpu/drm/drm_atomic_helper.c:3038
 drm_atomic_helper_commit_tail+0x60/0x510
 drivers/gpu/drm/drm_atomic_helper.c:1989
 commit_tail+0x2b1/0x3c0 drivers/gpu/drm/drm_atomic_helper.c:2074
 drm_atomic_helper_commit+0xa77/0xb10
 drivers/gpu/drm/drm_atomic_helper.c:2312

Fix this by validating in `cirrus_pci_probe()` that the PCI BAR0 resource
is not less than `CIRRUS_VRAM_SIZE`, returning `-ENODEV` if it is less.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.