CVE-2026-98905 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: Properly acquire queue buffers in CRIU restore
When kfd_queue_acquire_buffers() was split off from set_queue_properties_from_user(), set_queue_properties_from_criu() was missed. Thus, set_queue_properties_from_criu() is not filling out the buffer fields of queue_properties, which can come up when subsequent code expects them to be non-null.
Add the proper call to kfd_queue_acquire_buffers(), and also use the right cast types in set_queue_properties_from_criu() (which were missed at the same time)
(cherry picked from commit 88ed96abbbe27b70193544fbc1ee06448c274714)
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Analysis
by VulDB Data Team • 10/23/2026
The Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically the AMD Kernel Fusion Driver (amdkfd), contains a logic error in the handling of queue properties during Checkpoint and Restore In Userspace (CRIU) operations. CRIU is a tool that allows processes to be frozen and their state saved to disk, enabling them to be resumed on the same or different hosts. When restoring a process that utilizes AMD GPU queues, the kernel must reconstruct the internal data structures representing those queues. The vulnerability arises from an incomplete refactoring of the code responsible for setting queue properties from user space versus CRIU restore contexts. Specifically, when the function kfd_queue_acquire_buffers was separated from set_queue_properties_from_user to modularize buffer acquisition logic, the corresponding call in set_queue_properties_from_criu was inadvertently omitted. This oversight means that during a CRIU restore operation, the buffer fields within the queue properties structure are not properly initialized or populated with valid memory references.
This omission leads to a state where subsequent kernel code expects these buffer pointers to be non-null and valid for access, but instead finds them uninitialized or null. In the context of Linux kernel development, accessing invalid or null pointers typically results in a NULL pointer dereference, which triggers an immediate kernel panic or system crash. This constitutes a denial-of-service condition against the local system. An attacker who can trigger a CRIU restore operation for a process using AMD GPU queues could exploit this flaw to destabilize the host machine. The vulnerability is rooted in improper initialization of data structures during state restoration, which falls under CWE-908: Use of Uninitialized Resource and potentially CWE-476: NULL Pointer Dereference depending on the specific execution path taken after the property setting fails.
From a threat modeling perspective using the MITRE ATT&CK framework, this vulnerability aligns with techniques related to Denial of Service (T1499) as it impacts system availability by causing crashes. It also touches upon privilege escalation vectors if an attacker can leverage the resulting instability or memory corruption states to execute arbitrary code, although the primary impact described is stability-related. The flaw highlights a critical gap in regression testing for kernel subsystems where refactoring of complex initialization routines occurs without ensuring all call sites are updated consistently across different operational modes such as standard user-space interaction versus checkpoint restoration.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that reintroduces the missing kfd_queue_acquire_buffers() call within set_queue_properties_from_criu(). System administrators should ensure their systems are running a patched version of the AMD GPU driver and the associated kernel components. For environments where CRIU is actively used for high-availability or container migration purposes, it is imperative to verify that the specific commit 88ed96abbbe27b70193544fbc1ee06448c274714 has been integrated into the distribution kernel. Additionally, developers working on similar subsystems should enforce stricter code review processes for refactoring tasks to ensure that all entry points, including those used by specialized tools like CRIU, are consistently updated and validated against expected invariants such as non-null pointer requirements.