Linux LTS Kernels 6.18.42, 6.12.101, and 6.6.148 Fix ksmbd, dm-verity, BPF, and AMDGPU

by Geth Author

On August 3, 2026, kernel maintainers Greg Kroah-Hartman and Sasha Levin pushed stable updates across three active LTS lines: v6.18.42, v6.12.101, and v6.6.148. All three releases share a common set of critical security patches, plus a substantial AMDGPU driver overhaul that affects every system running an AMD GPU on one of these long-term kernel lines.

Security Fixes Across All Three Tracks

The patches common to all three LTS lines cover three distinct subsystems:

  • ksmbd ACL validation: A flaw in the kernel's in-kernel SMB server could allow unauthorized file access on systems using ksmbd for network file sharing. Patched in all three tracks.
  • dm-verity buffer overflows: Device mapper integrity verification contained a buffer overflow condition that could be triggered during block device reads. dm-verity is widely used in Android, ChromeOS, and hardened Linux distributions to verify partition integrity at boot — this fix matters for embedded and security-focused deployments.
  • BPF memory safety: The extended Berkeley Packet Filter subsystem received fixes addressing conditions where BPF programs could access memory outside intended boundaries. BPF is used for networking, observability, and security enforcement on virtually every modern Linux server.

AMDGPU Gets a Major Stability Overhaul

The most significant structural change in these releases is to the AMDGPU driver. Driver maintainers converted BUG_ON() calls to WARN_ON() throughout the driver's gfx8 through gfx12 code paths — covering hardware from the Fiji era (2015) all the way up to current RDNA 4 GPUs.

This is more than a cosmetic change. BUG_ON() triggers an immediate kernel panic and system halt when its condition is met; WARN_ON() logs the condition and continues execution. The old behavior meant a GPU driver edge case — a race, an unexpected state — could crash your entire machine instantly with no recovery possible. With WARN_ON(), those conditions produce log entries and let the system keep running, which is the right trade-off for driver code where a panic is rarely necessary for system integrity.

The update also backports a 1,900-line refactor of the DRM buddy allocator — the memory manager used by AMD's display and compute engines — improving correctness and reducing fragmentation under long-running GPU workloads.

Who This Affects

All three kernel lines receiving these updates — 6.18, 6.12, and 6.6 — are actively maintained through at least December 2028. Distributions shipping from these lines include Ubuntu 24.04 LTS, Debian Bookworm, and RHEL-family systems.

For server operators running AMD GPUs under workloads like ML training, video processing, or GPU-accelerated databases, the AMDGPU stability work is worth applying promptly. The security fixes for ksmbd, dm-verity, and BPF are straightforward updates any LTS system should take via its distribution's normal update mechanism.

The full diff and commit details are available on the stable kernel update announcement.