From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-63881][MODERATE 7.0] drm/amdkfd: fix a vulnerability of integer overflow in kfd debugger Date: Sun, 19 Jul 2026 20:09:37 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-63881 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: 4e5f808b454167cc58d7084a407a554d8ddc694d List-Id: CVE: CVE-2026-63881 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/amdkfd: fix a vulnerability of integer overflow in kfd debugger Commit: 4e5f808b454167cc58d7084a407a554d8ddc694d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e5f808b454167cc58d7084a407a554d8ddc694d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63881 Analysis date: Sun, 19 Jul 2026 20:09:37 -0400 ActionableScore: 5 ActionableScore lower bound: 3 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: An integer overflow in AMD KFD debugger `get_queue_ids()` on 32-bit `size_t` builds can cause an undersized `memdup_user()` allocation and possible kernel out-of-bounds read, leading at least to local DoS and requiring manual review for limited confidentiality or integrity impact. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63881 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63881 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-2026-63881 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-190;CWE-131;CWE-125;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 integer overflow in the amdkfd debugger get_queue_ids path can occur when num_queues is multiplied by sizeof(uint32_t) on a 32-bit size_t build. The wrapped size can make memdup_user allocate and copy less memory than the later queue id processing expects, creating an out of bounds read condition in kernel context. For the CVSS the PR:L is used because triggering requires a local user context with access to the AMD KFD debugger or device interface, but does not necessarily require full administrator privileges. The issue is not network reachable and is limited to local attack surface. Impact is at least local denial of service via kernel crash. In the paranoid interpretation it may also allow limited confidentiality or integrity impact due to kernel heap out of bounds reads, but no direct arbitrary write primitive is shown by the patch context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4) SKIP CVE-2026-63881 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE SIMPLEFIX HARDWARE INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK 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. The affected path is a local AMD KFD debugger or device interface path, likely reachable by a local user with access to the GPU/KFD device node rather than requiring full host root. * Memory corruption, Weak/indirect corruption candidate: +1. The integer overflow can produce an undersized `memdup_user()` allocation, and later code may process `num_queues` entries, creating a kernel out-of-bounds read condition. * Reliable kernel crash / strong DoS: +1. A kernel OOB read in queue-management context can plausibly crash the kernel or destabilize the KFD queue-management path. * Privileged kernel/device-management memory corruption path: +1. The bug is in GPU queue/debugger management code where malformed local input can affect trusted kernel-side queue handling. * Legacy / non-default execution mode: -1. The overflow is specifically relevant to 32-bit `size_t` builds, while typical modern AMD KFD deployments are 64-bit. Paranoid additional signals: * Confidentiality impact plausible: +1. A kernel heap OOB read may theoretically expose adjacent kernel data if any later path reflects or uses copied queue IDs in an observable way. * Integrity impact plausible: +1. Bogus queue IDs derived from adjacent memory could theoretically affect incorrect queue selection or queue-control behavior, although no direct write primitive is shown. No strong LPE signal is awarded. No arbitrary write, UAF reclaim, callback control, or type confusion is demonstrated. ## 3. Reachability analysis A local process with access to the AMD KFD debugger or device interface is the realistic trigger. This is not network reachable. Namespace or container relevance depends on whether `/dev/kfd` or GPU render nodes are delegated into the container, so PR can be lower than full root in practical deployments. The main limiting factor is the 32-bit `size_t` build condition, which makes broad default exposure lower on common 64-bit systems. Call-site confidence: medium, because the helper and surrounding function context are visible, but the full downstream processing of returned queue IDs is not included. ## 4. Severity interpretation This is more than an ordinary correctness fix because it is an integer overflow leading to an undersized kernel allocation and possible OOB read. Realistically, it behaves like local DoS on affected 32-bit builds. The paranoid view supports Actionable Moderate handling because limited confidentiality or integrity effects are plausible from kernel heap OOB reads, but the patch does not support Strong Important classification without evidence of an OOB write, UAF, object replacement, or privilege-escalation primitive. ## 5. One-sentence report phrase An integer overflow in AMD KFD debugger `get_queue_ids()` on 32-bit `size_t` builds can cause an undersized `memdup_user()` allocation and possible kernel out-of-bounds read, leading at least to local DoS and requiring manual review for limited confidentiality or integrity impact. ## 6. Manual review recommendation MANUAL CHECK REQUIRED. Reason: integer overflow plus undersized kernel allocation is a concrete bug class with possible OOB read in a device-management path, and the final impact depends on downstream queue ID processing not fully visible in the provided patch. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amdkfd: fix a vulnerability of integer overflow in kfd debugger Commit: 4e5f808b454167cc58d7084a407a554d8ddc694d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e5f808b454167cc58d7084a407a554d8ddc694d Commit description: get_queue_ids() computes array_size = num_queues * sizeof(uint32_t), which could overflow on 32-bit size_t build. using array_size() instead, it saturates to SIZE_MAX on overflow. Signed-off-by: Eric Huang Acked-by: Alex Deucher Signed-off-by: Alex Deucher (cherry picked from commit 2d57a04 ) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.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=4e5f808b454167cc58d7084a407a554d8ddc694d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-63881 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63881 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).