From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46197][MODERATE 7.0] drm/amdkfd: validate SVM ioctl nattr against buffer size Date: Sat, 01 Aug 2026 09:51:16 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46197 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: 91c6dc5a41695d02dfc6299f106ac38a6c493e52 List-Id: CVE: CVE-2026-46197 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/amdkfd: validate SVM ioctl nattr against buffer size Commit: 91c6dc5a41695d02dfc6299f106ac38a6c493e52 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=91c6dc5a41695d02dfc6299f106ac38a6c493e52 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46197 Analysis date: Sat, 01 Aug 2026 09:51:16 -0400 ActionableScore: 5 ActionableScore lower bound: 3 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: A user-controlled `nattr` value in the AMD KFD SVM ioctl was not validated against the actual ioctl buffer size, allowing a local process with `/dev/kfd` access to trigger out-of-bounds kernel buffer access and likely DoS, with limited C/I concern in the paranoid interpretation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46197 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46197 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 7.0 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-2026-46197 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-125;*CWE-20;CWE-130;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.6';DESCR 'An out of bounds access in the AMD KFD SVM ioctl can occur because the user controlled nattr count was not validated against the actual ioctl buffer size. kfd_ioctl_svm can then process more attrs entries than were copied into the kernel buffer, causing reads beyond the supplied data and possible kernel memory access outside the allocated object. A local user or process with access to /dev/kfd can trigger this through the SVM ioctl. For the CVSS the PR:L is used because many GPU compute systems delegate KFD access to non root users through device permissions or render groups. The issue is not network reachable. Impact is at least local denial of service via kernel crash, and the paranoid interpretation keeps C:L and I:L because an out of bounds read in kernel control data may expose or influence limited state even though no arbitrary write primitive is shown.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4) SKIP CVE-2026-46197 SKIP No affected files built, so skip this CVE NO - - unknown MAYBE WRITE OOB HARDWARE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum** ## 2. Signal breakdown Conservative signals: * Local unprivileged trigger: +1. A local process with access to `/dev/kfd` can issue `AMDKFD_IOC_SVM`. On many GPU compute systems this access is delegated to non-root users through device permissions or render/video-style groups. * Memory corruption, weak/indirect corruption candidate: +1. The patch validates a user-controlled `nattr` count against the ioctl buffer size, preventing out-of-bounds access past the flexible `attrs` array. The patch supports OOB access, but not an OOB write, UAF, arbitrary write, or reclaim primitive. * Reliable kernel crash / strong DoS: +1. Processing attributes beyond the copied ioctl buffer can plausibly dereference invalid kernel memory or interpret unrelated kernel data as SVM attributes, making a local kernel crash realistic. Paranoid additional signals: * Confidentiality impact plausible: +1. OOB reads from adjacent kernel buffer data may expose or use unintended kernel data internally, although no direct user-visible leak is demonstrated. * Integrity impact plausible: +1. Misinterpreting adjacent memory as SVM attributes could influence SVM handling state in a limited way, but no controlled write primitive is shown. Signals not awarded: * No remote/network trigger. This is a local ioctl path. * No strong LPE bonus. The patch does not show attacker-controlled reclaim, arbitrary write, type confusion, callback control, or refcount takeover. * No high-control GPU API bonus. The bug is in a GPU ioctl, but the patch only shows count validation for a variable-length buffer, not attacker control over object lifetime, DMA mappings, callbacks, or page ownership. * No admin/root penalty. Access to KFD devices is commonly delegated to non-root GPU users, so PR:L is the more actionable interpretation. ## 3. Reachability analysis A local user or process that can open the AMD KFD device node and issue `AMDKFD_IOC_SVM` can trigger the vulnerable path. This generally requires AMDGPU KFD support and SVM-enabled kernel configuration, so exposure is limited to systems with AMD GPU compute functionality, but the interface is still an ordinary local device API on such systems. Namespaces and containers may matter if `/dev/kfd` is passed into a container or delegated to a workload. In that case the trigger can come from a reduced-privilege container or service account rather than full host root. The issue is not network reachable. Call-site confidence: high. The patch shows the generic ioctl dispatch path adding a `validate` hook before calling `kfd_ioctl_svm`, and the SVM ioctl is explicitly wired to `kfd_ioctl_svm_validate`. ## 4. Severity interpretation This behaves more like an actionable Moderate than an ordinary low-priority Moderate. The realistic impact is local DoS through an OOB access in a kernel ioctl path. The theoretical impact can extend to limited confidentiality or integrity concerns because the kernel may process memory beyond the intended user-supplied `attrs` buffer, but the patch does not demonstrate a strong privilege-escalation primitive. It should not be classified as an Important-class issue based only on the supplied patch. There is no evidence of OOB write, UAF, double-free, arbitrary write, page-cache corruption, or controlled object replacement. However, because this is a local kernel OOB access reachable through a delegated GPU device interface, it should not be auto-closed without manual review. ## 5. One-sentence report phrase A user-controlled `nattr` value in the AMD KFD SVM ioctl was not validated against the actual ioctl buffer size, allowing a local process with `/dev/kfd` access to trigger out-of-bounds kernel buffer access and likely DoS, with limited C/I concern in the paranoid interpretation. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Manual review is required because this is a local kernel out-of-bounds access in an ioctl path exposed to non-root GPU users on many systems. The current evidence supports actionable Moderate handling, while LPE remains unproven without a stronger corruption primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amdkfd: validate SVM ioctl nattr against buffer size Commit: 91c6dc5a41695d02dfc6299f106ac38a6c493e52 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=91c6dc5a41695d02dfc6299f106ac38a6c493e52 Commit description: Validate nattr field against the buffer size, preventing out-of-bounds buffer access via user-controlled attribute count. Reviewed-by: Amir Shetaia Signed-off-by: Alysa Liu Signed-off-by: Alex Deucher (cherry picked from commit 5eca8bf ) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/amdkfd/kfd_chardev.c drivers/gpu/drm/amd/amdkfd/kfd_priv.h 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=91c6dc5a41695d02dfc6299f106ac38a6c493e52 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46197 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46197 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: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 6.6 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: 5 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 7.0 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).