From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68447][MODERATE REGULAR] drm/amdkfd: clamp v9 CRIU control stack checkpoint copy to BO size Date: Tue, 11 Aug 2026 21:55:23 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68447 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 List-Id: CVE: CVE-2026-68447 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/amdkfd: clamp v9 CRIU control stack checkpoint copy to BO size Commit: a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68447 Analysis date: Tue, 11 Aug 2026 21:55:23 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline Actionable Moderate / manual review required Manual review required: YES Summary: A local out-of-bounds read in the AMD KFD CRIU checkpoint path can copy data past the control stack BO into userspace, causing a kernel or driver memory disclosure when affected GPU checkpoint functionality is reachable. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68447 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68447 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE REGULAR Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-68447 MODERATE CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N';CWE-125;CWE-126;*CWE-200;BEST CVSS score: '5.5';DESCR 'An out-of-bounds read in the AMD KFD CRIU checkpoint path can occur because the v9 MQD control stack copy size is taken from cp_hqd_cntl_stack_size without bounding it to the allocated control stack BO. If this hardware derived size is larger than the queue control stack allocation, memcpy can read past the BO into adjacent GTT memory and copy that data to userspace through the checkpoint output. For the CVSS the PR:L is used because triggering requires local access to the AMD KFD or CRIU checkpoint interface, but such access may be available to non-root GPU compute users on systems where /dev/kfd is exposed to render or video group users. The issue is not network reachable. Impact is a local confidentiality breach due to kernel or driver memory disclosure. No direct integrity impact or privilege escalation primitive is shown by the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Actionable Moderate / manual review required (with actual score 4) SKIP CVE-2026-68447 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE LEAK LOG HARDWARE DEBUGFS MEMORY DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline Actionable Moderate / manual review required** ## 2. Signal breakdown * Local unprivileged trigger: +1 Triggering requires local access to AMD KFD / CRIU checkpoint functionality. On GPU compute systems, `/dev/kfd` may be available to non-root users in render/video groups. * Confidentiality impact plausible: +1 The patch explicitly describes an out-of-bounds read past the allocated control stack BO into adjacent GTT memory, copied back to userspace. * Privileged kernel/device-management disclosure path: +1 The bug is in a GPU kernel driver checkpoint path and leaks data from kernel-managed GPU/GTT memory. This is not just a user-buffer bounds issue. * Firmware / hardware-mediated size influence: +1 for paranoid only The unsafe copy length comes from the hardware-derived `cp_hqd_cntl_stack_size` field. This does not make it remotely reachable, but it supports a higher manual-review score because the kernel trusted a device-provided size without bounding it to the BO allocation. * Weak corruption / limited read-only OOB: +0 This is a concrete OOB read and disclosure primitive, but not an OOB write, UAF, double free, refcount bug, or type confusion. * No LPE bonus: +0 The patch supports information disclosure, not a direct privilege escalation primitive. * No remote/network exposure: +0 The affected path is local GPU/CRIU checkpoint handling, not packet parsing or a network service. * No rare-config penalty in the main score The path is hardware and feature dependent, but still reachable through ordinary local GPU interfaces on affected AMD KFD systems. I would not auto-downgrade it solely as rare hardware. ## 3. Reachability analysis A local user or local process with access to AMD KFD queue checkpoint functionality can potentially trigger the affected path. In typical desktop or HPC GPU deployments, access to `/dev/kfd` may be delegated to non-root users through GPU-related groups, so PR:L is the practical assumption rather than PR:H. Namespaces or containers may matter if GPU devices are passed through or exposed into containers. A container user with access to the KFD device node could plausibly reach the same driver path, depending on device cgroup and runtime configuration. The issue is not network reachable. Exploitation depends on affected AMD GPU generations, KFD enabled, CWSR/checkpoint support, and the relevant v9/v9.4.3 MQD checkpoint path. Call-site confidence: high. The patch directly shows `memcpy()` using an unbounded hardware-derived size and then replacing it with `min(cp_hqd_cntl_stack_size, mm->ctl_stack_size)`. ## 4. Severity interpretation This behaves more like an actionable Moderate information disclosure than an Important memory-corruption issue. The realistic impact is local disclosure of adjacent GTT/kernel-driver memory to userspace through checkpoint output. Theoretical exploit chaining is possible if the leaked data contains useful kernel or driver state, but the patch does not show a write primitive, object lifetime corruption, callback control, type confusion, or direct LPE path. Therefore, Important-class scoring is not justified from this patch alone, but manual review is warranted because the disclosure primitive is concrete. ## 5. One-sentence report phrase A local out-of-bounds read in the AMD KFD CRIU checkpoint path can copy data past the control stack BO into userspace, causing a kernel or driver memory disclosure when affected GPU checkpoint functionality is reachable. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a concrete kernel-driver OOB read with user-visible disclosure, not merely a crash or validation cleanup. It should not be auto-closed even though the current evidence supports confidentiality impact only and no direct privilege escalation primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amdkfd: clamp v9 CRIU control stack checkpoint copy to BO size Commit: a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 Commit description: 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. Signed-off-by: Yongqiang Sun Reviewed-by: David Francis Signed-off-by: Alex Deucher (cherry picked from commit 6c2abd0 ) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager.h drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a0d87beb2660a5098b2b0ecdc1e96810a9074ea9 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68447 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68447 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: Not available The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N The Best / paranoid CVSS score: 5.5 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: 3 Paranoid ActionableScore: 4 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).