In the Linux kernel, the following vulnerability has been resolved: drm/vc4: Prevent shader BO mappings from becoming writable vc4_gem_object_mmap()… (CVE-2026-68445)
A vulnerability in the Linux kernel's drm/vc4 driver allowed shader buffer objects (BOs) to be mapped writable by userspace after initial read-only mapping, bypassing the shader validation process. This flaw permitted modification of validated shader code, which should remain immutable to ensure GPU trust. The issue was resolved by clearing the VM_MAYWRITE flag on read-only mappings, preventing writable upgrades via mprotect().
AI Analysis
Technical Summary
The Linux kernel's drm/vc4 driver had a vulnerability where vc4_gem_object_mmap() rejected writable mappings of validated shader BOs but left the VM_MAYWRITE flag set. This allowed userspace to first map the BO read-only and then escalate to writable using mprotect(), enabling modification of shader code after validation. Since the GPU trusts validated shaders, this bypassed the validation mechanism. The fix involved clearing the VM_MAYWRITE flag on read-only mappings to prevent writable upgrades, similar to the approach used by the i915 driver.
Potential Impact
Userspace could modify validated shader code after it was trusted by the GPU, potentially leading to unauthorized code execution or GPU behavior manipulation. This undermines the integrity of shader validation, which is critical for secure GPU operation.
Mitigation Recommendations
A fix has been implemented in the Linux kernel drm/vc4 driver to clear the VM_MAYWRITE flag on read-only mappings of validated shader BOs, preventing writable upgrades. Users should update to the fixed kernel version once available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
In the Linux kernel, the following vulnerability has been resolved: drm/vc4: Prevent shader BO mappings from becoming writable vc4_gem_object_mmap()… (CVE-2026-68445)
Description
A vulnerability in the Linux kernel's drm/vc4 driver allowed shader buffer objects (BOs) to be mapped writable by userspace after initial read-only mapping, bypassing the shader validation process. This flaw permitted modification of validated shader code, which should remain immutable to ensure GPU trust. The issue was resolved by clearing the VM_MAYWRITE flag on read-only mappings, preventing writable upgrades via mprotect().
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel's drm/vc4 driver had a vulnerability where vc4_gem_object_mmap() rejected writable mappings of validated shader BOs but left the VM_MAYWRITE flag set. This allowed userspace to first map the BO read-only and then escalate to writable using mprotect(), enabling modification of shader code after validation. Since the GPU trusts validated shaders, this bypassed the validation mechanism. The fix involved clearing the VM_MAYWRITE flag on read-only mappings to prevent writable upgrades, similar to the approach used by the i915 driver.
Potential Impact
Userspace could modify validated shader code after it was trusted by the GPU, potentially leading to unauthorized code execution or GPU behavior manipulation. This undermines the integrity of shader validation, which is critical for secure GPU operation.
Mitigation Recommendations
A fix has been implemented in the Linux kernel drm/vc4 driver to clear the VM_MAYWRITE flag on read-only mappings of validated shader BOs, preventing writable upgrades. Users should update to the fixed kernel version once available. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-rw5p-xff5-86qj
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-68445"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a7c9b69bf8831d539cdf6a3
Added to database: 08/12/2026, 16:12:25 UTC
Last enriched: 08/12/2026, 17:18:01 UTC
Last updated: 08/13/2026, 00:41:14 UTC
Views: 2
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