CVE-2026-68447 in Linux
Summary
by MITRE • 08/12/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: clamp v9 CRIU control stack checkpoint copy to BO size
CRIU checkpoint copies the MQD control stack using cp_hqd_cntl_stack_size from hardware without bounding it to the allocated BO region. If the HW field is larger than the queue's control stack allocation, memcpy reads past the BO into adjacent GTT memory and can leak kernel data to userspace.
Store the page-aligned control stack BO size in mqd_manager and clamp checkpoint copies and reported checkpoint sizes to min(cp_hqd_cntl_stack_size, mm->ctl_stack_size). Apply the same bound for multi-XCC v9.4.3 checkpoint layout.
(cherry picked from commit 6c2abd0ec09e86c6323010673766f76050e28aa3)
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability in question affects the Linux kernel's graphics driver subsystem, specifically within the amdkfd component responsible for managing AMD GPU compute queues. This issue resides in the CRIU (Checkpoint/Restore in Userspace) functionality that enables saving and restoring process states, particularly impacting graphics processing units running on AMD hardware. The flaw manifests when the kernel attempts to checkpoint compute queue control stacks during system suspend/resume operations or application migration scenarios.
The core technical flaw stems from improper bounds checking during memory copy operations involving GPU queue management data structures. During CRIU checkpoint procedures, the system retrieves the control stack size information directly from hardware registers through the cp_hqd_cntl_stack_size field without applying any validation against the actual allocated buffer object region. This oversight creates a potential for buffer over-read conditions where the memcpy operation extends beyond the intended memory boundaries.
When the hardware-reported control stack size exceeds the allocated buffer object capacity, the memory copy operation reads data from adjacent GTT (Graphics Translation Table) memory regions that contain kernel-sensitive information. This unauthorized memory access creates a data leakage scenario where kernel-space data becomes accessible to unprivileged user processes through the checkpoint mechanism, effectively compromising system security and confidentiality.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a privilege escalation vector that could potentially allow malicious users to extract sensitive kernel memory contents. The flaw affects systems utilizing AMD GPU compute capabilities with CRIU functionality enabled, particularly those running kernel versions containing the vulnerable amdkfd implementation. Attackers could leverage this vulnerability to gain insights into kernel memory layouts, potentially aiding in more sophisticated exploitation techniques.
The mitigation strategy involves implementing proper bounds checking by storing the page-aligned buffer object size within the mqd_manager data structure and enforcing clamping of all checkpoint copy operations and reported sizes against the minimum value between the hardware-reported size and the actual allocated BO size. This approach ensures that memory operations remain confined to their intended boundaries regardless of hardware register values. The fix also addresses multi-XCC v9.4.3 checkpoint layouts, ensuring comprehensive protection across different AMD GPU architectures and configuration scenarios.
This vulnerability aligns with CWE-121, which covers stack-based buffer overflow conditions, and relates to ATT&CK technique T1059.001 for command and scripting interpreter execution, as the leaked kernel data could enable more sophisticated attack vectors. The issue demonstrates a classic case of insufficient input validation in kernel space operations, where hardware abstraction layers fail to properly validate and constrain external inputs before memory operations occur, creating potential security exposure pathways that violate fundamental secure coding practices.