Bug 2482636 (CVE-2026-46209)

Summary:	CVE-2026-46209 kernel: drm/gem: Fix inconsistent plane dimension calculation in drm_gem_fb_init_with_funcs()
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Direct Rendering Manager (DRM) Graphics Execution Manager (GEM) component. This vulnerability arises from an inconsistent calculation of plane dimensions, which can lead to incorrect memory allocation checks. A local attacker could exploit this by creating a specially crafted Graphics Execution Manager (GEM) object that bypasses security validations. This could allow the GPU to access memory outside its designated area, potentially leading to memory corruption, information disclosure, or the execution of unauthorized code.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-28 11:06:59 UTC

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().

Comment 1 Keith Grant 2026-05-28 13:19:17 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052834-CVE-2026-46209-e4e9@gregkh/T

Comment 3 errata-xmlrpc 2026-07-02 13:42:29 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:34911 https://access.redhat.com/errata/RHSA-2026:34911

Comment 4 errata-xmlrpc 2026-07-06 19:57:17 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:36018 https://access.redhat.com/errata/RHSA-2026:36018

Comment 5 errata-xmlrpc 2026-07-07 19:25:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:36348 https://access.redhat.com/errata/RHSA-2026:36348

Comment 6 errata-xmlrpc 2026-07-07 19:40:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:36349 https://access.redhat.com/errata/RHSA-2026:36349

Comment 7 errata-xmlrpc 2026-07-15 15:54:25 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:40068 https://access.redhat.com/errata/RHSA-2026:40068

Comment 8 errata-xmlrpc 2026-07-16 07:16:20 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:40760 https://access.redhat.com/errata/RHSA-2026:40760

Comment 9 errata-xmlrpc 2026-07-22 06:23:43 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:43231 https://access.redhat.com/errata/RHSA-2026:43231

Comment 10 errata-xmlrpc 2026-07-23 11:57:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:44385 https://access.redhat.com/errata/RHSA-2026:44385

Comment 11 errata-xmlrpc 2026-07-29 00:52:06 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:47632 https://access.redhat.com/errata/RHSA-2026:47632

Comment 12 errata-xmlrpc 2026-07-29 01:06:34 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:47633 https://access.redhat.com/errata/RHSA-2026:47633

Comment 13 errata-xmlrpc 2026-07-29 22:42:22 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:47739 https://access.redhat.com/errata/RHSA-2026:47739