CVE-2026-46197: drm/amdkfd: validate SVM ioctl nattr against buffer size

Synopsis

An out-of-bounds buffer access vulnerability exists in the Linux kernel's AMD GPU driver (drm/amdkfd), specifically in the SVM (Shared Virtual Memory) ioctl handler. The flaw is reachable locally by a low-privileged user who can submit crafted ioctl calls with a manipulated attribute count (nattr) field that exceeds the actual buffer size. Successful exploitation gives an attacker full read, write, and crash capability over the affected host. A patched-image rebuild is available on HarborGuard for environments running affected kernel versions.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityNot required

  The attacker needs an existing shell or process on the host; no network path to the vulnerable code is required.

• AuthenticationRequired

  Any low-privilege local account is sufficient to issue the crafted ioctl; no elevated or administrative credentials are needed.

• Victim interactionNot required

  No user interaction is required; the attacker triggers the vulnerability entirely through their own process.

• Attack complexityDetail

  Exploit reliability is high and the attack is condition-free, with no race conditions or special memory layout requirements needed.

Blast Radius

• A successful attacker reads arbitrary kernel memory, including credentials, keys, and session data accessible to the kernel at the time of the read.
• The attacker writes to arbitrary kernel memory, enabling privilege escalation to root or modification of security-relevant kernel state.
• The attacker crashes the affected kernel, taking down all workloads running on that host.
• Any container sharing the host kernel is exposed to the same impact, since the vulnerability sits in a kernel driver rather than userspace.