From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68324][MODERATE 7.0] iommu/intel: Fix out-of-bounds memset in dmar_latency_disable() [ Upstream Date: Mon, 10 Aug 2026 13:33:14 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68324 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: 3078d82e7fe9048a2b90a992e71af7cd7ef881fa List-Id: CVE: CVE-2026-68324 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: iommu/intel: Fix out-of-bounds memset in dmar_latency_disable() [ Upstream Commit: 3078d82e7fe9048a2b90a992e71af7cd7ef881fa Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3078d82e7fe9048a2b90a992e71af7cd7ef881fa Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68324 Analysis date: Mon, 10 Aug 2026 13:33:14 -0400 ActionableScore: 5 ActionableScore lower bound: 3 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: An out-of-bounds memset in Intel IOMMU latency monitoring can zero memory past the selected latency_statistic entry when disabling a nonzero type, causing adjacent kernel memory corruption with realistic DoS impact and a limited but review-worthy LPE concern. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68324 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68324 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-2026-68324 MODERATE CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-119;CWE-131;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'An out-of-bounds memset in dmar_latency_disable can clear more than the selected latency_statistic entry. When type is greater than zero, the memset starts at lstat(type) but uses the size of the full array, so it writes past the allocated latency statistics array and can corrupt adjacent kernel memory. For the CVSS the PR:L in the paranoid score reflects environments where a local user, reduced capability root, service account, or delegated perf/debugfs control path can reach the DMAR latency performance monitor interface. The issue is not network reachable and requires local interaction with IOMMU latency monitoring controls. Impact is at least local denial of service via kernel memory corruption and in worst case may allow confidentiality or integrity impact if the adjacent corrupted memory can be shaped or reused in an exploitable way.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4) YES WRITE OOB SIMPLEFIX LINUS MEMORY DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: **3** * Paranoid score: **5** * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum** ## 2. Signal breakdown ### Conservative score: 3 * **Generic memory corruption: +2** The patch fixes an explicit out-of-bounds `memset()` in kernel memory. For `type > 0`, the memset starts at `lstat[type]` but clears `DMAR_LATENCY_NUM` entries, writing past the allocated array. * **Privileged kernel/device-management memory corruption path: +1** The bug is in Intel IOMMU / VT-d latency performance monitoring, a trusted device-management subsystem. * **Integrity impact plausible: +1** Adjacent kernel memory is overwritten with zeroes, so kernel state integrity can be affected. * **Availability impact realistic: +1** Adjacent kernel memory corruption can plausibly cause a crash or unstable host behavior. * **Requires admin/root/CAP-like access in typical deployments: -2** Reaching DMAR latency performance monitor controls is likely restricted to root or privileged debugfs/perf-style interfaces. Total: `2 + 1 + 1 + 1 - 2 = 3` ### Paranoid score: 5 * **Generic memory corruption: +2** Explicit OOB write into adjacent kernel memory. * **Weak LPE concern: +1** The overwrite is fixed zero data and target control is not demonstrated, but adjacent object corruption in kernel memory can be exploitable depending on layout. * **Privileged kernel/device-management memory corruption path: +1** IOMMU/VT-d monitoring code is a sensitive kernel subsystem. * **Integrity impact plausible: +1** Kernel memory beyond the intended array is modified. * **Availability impact realistic: +1** Kernel crash or device-management state corruption is plausible. * **Privilege penalty refined: -1** Typical access is privileged, but a reduced-capability root, service account, or delegated debug/perf control path could make this less than full host-root in practical risk terms. * **No attacker-controlled payload or precise overwrite target: -1** The payload is zeroes and the patch does not show controlled object replacement, reclaim, callback control, or arbitrary write. Total: `2 + 1 + 1 + 1 + 1 - 1 - 1 = 5` ## 3. Reachability analysis The bug is local, not network reachable. A realistic trigger likely requires access to Intel IOMMU latency monitoring controls, which are normally privileged and may depend on kernel configuration and debug/performance monitoring exposure. Namespaces or containers usually do not expose this path to unprivileged users, but delegated debugfs/perf/device-management access could lower the practical privilege requirement in some environments. Call-site confidence: **medium**. The changed function and bug primitive are clear, but the provided patch does not include all callers or the exact user-facing control path. ## 4. Severity interpretation This is not an ordinary low-risk cleanup because the patch fixes a concrete out-of-bounds write in kernel memory. However, it is also not a strong Important by default because the overwrite is constrained to zeroing adjacent memory and the patch does not show attacker-controlled payload, controlled target selection, reclaim, type confusion, or a demonstrated LPE path. Realistically, this behaves like an **Actionable Moderate** issue that should not be auto-closed. Paranoid handling is justified because kernel OOB writes in device-management code can be underestimated before manual layout and call-path review. ## 5. One-sentence report phrase An out-of-bounds memset in Intel IOMMU latency monitoring can zero memory past the selected latency_statistic entry when disabling a nonzero type, causing adjacent kernel memory corruption with realistic DoS impact and a limited but review-worthy LPE concern. ## 6. Manual review recommendation **MANUAL CHECK REQUIRED** Reason: the patch explicitly fixes an out-of-bounds kernel memory write. Even though the overwrite is constrained and typically privileged, adjacent memory corruption in IOMMU/device-management code warrants manual call-path and layout review. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: iommu/intel: Fix out-of-bounds memset in dmar_latency_disable() [ Upstream Commit: 3078d82e7fe9048a2b90a992e71af7cd7ef881fa Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3078d82e7fe9048a2b90a992e71af7cd7ef881fa Changed files: drivers/iommu/intel/perf.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=3078d82e7fe9048a2b90a992e71af7cd7ef881fa ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68324 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68324 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:H/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7 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).