CVE-2026-46209: DRM plane dimension mismatch leads to buffer overread
CVE-2026-46209 Published on May 28, 2026
drm/gem: Fix inconsistent plane dimension calculation in drm_gem_fb_init_with_funcs()
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().
Products Associated with CVE-2026-46209
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 and below 6b992591e04f2cce813bcf239b354f375bbf84d3 is affected.
- Version 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 and below 1da4ab7189f1064b3b712b388772c008b4d82580 is affected.
- Version 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 and below 1a17ea9861e89585361caa8bc231bd22dc6dbe7d is affected.
- Version 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 and below c5fc49d8470c5ebf3b41607600f277158f159950 is affected.
- Version 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 and below 3d4c2268bd7243c3780fe32bf24ff876da272acf is affected.
- Version 4.14 is affected.
- Before 4.14 is unaffected.
- Version 6.6.140, <= 6.6.* is unaffected.
- Version 6.12.90, <= 6.12.* is unaffected.
- Version 6.18.32, <= 6.18.* is unaffected.
- Version 7.0.9, <= 7.0.* is unaffected.
- Version 7.1-rc2, <= * is unaffected.