From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99047][LOW] gve: fix XSK buffer leak when rings are stopped Date: Mon, 26 Oct 2026 22:37:21 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99047 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 506f9de069d07a72b9887ce3edd2fdf32f4953aa List-Id: CVE: CVE-2026-99047 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: gve: fix XSK buffer leak when rings are stopped Commit: 506f9de069d07a72b9887ce3edd2fdf32f4953aa Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=506f9de069d07a72b9887ce3edd2fdf32f4953aa Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99047 Analysis date: Mon, 26 Oct 2026 22:37:21 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: GVE ring reset leaks posted AF_XDP zero-copy buffers, potentially depleting the affected queue without evidence of memory corruption or broader host compromise. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99047 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99047 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: LOW Manual review required: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-99047 LOW https://www.kernelcve.org/list/?q=CVE-2026-99047 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: 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:N/I:N/A:L';*CWE-772;*CWE-401;CWE-404;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'GVE DQO RX ring reset does not return posted AF_XDP zero copy XSK buffers when queues are stopped, so buffers attached to allocated buf_state entries become unavailable to the XSK pool. Repeated stop and reset cycles may progressively deplete buffers and disrupt the affected AF_XDP queue, but there is no evidence of memory corruption, information disclosure, a kernel crash, or a direct remote trigger. For the CVSS the PR:L value reflects that a local process must use AF_XDP zero copy, while reliable control of queue stopping may require network administration or an operational device reset. The demonstrated impact is persistent resource retention and localized availability degradation. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 3.3 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE REMOTE INIT SIMPLEFIX LEAK NETWORK LINUS DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1 * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 1 * Paranoid score: 1; no technically supported additional impact. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Concrete persistent kernel resource leak: ring reset omitted `xsk_buff_free()` for allocated `buf_state` entries, permanently withholding posted XSK buffers from normal pool reuse. * +0 Strong DoS: progressive queue-buffer depletion and localized disruption are plausible, but host-wide exhaustion, kernel crash, or persistent system outage is not shown. * +0 Local-unprivileged trigger: AF_XDP use is local, but the evidence does not establish that the same low-privilege actor can stop/reset the queue. * No UAF, OOB access, memory overwrite, authorization bypass, disclosure, protected-state corruption, or cross-boundary primitive is shown. * NEW52 B5-R and NEW53 B3-PENDING do not apply: there is neither an OOB write nor a shared-backing write. 3. Reachability analysis The affected configuration requires GVE DQO RX with AF_XDP zero-copy buffers posted to the NIC, followed by queue stopping/reset. A local process may operate the XSK, but control over the required stop/reset operation is unresolved and may involve network administration or an operational device reset. The evidence does not identify the governing capability namespace, prove a complete namespace-scoped trigger, establish host UID 0, or demonstrate special attacker-controlled retry timing. 4. Primitive and severity reading The exact defect is omitted resource return during ring teardown, not stale-object use: the fix frees each retained `xsk_buff` and clears its pointer. The shown consequence is XSK-buffer retention and affected-queue availability degradation. It is CLASS_C resource-management behavior, with no useful corruption primitive or Important-grade boundary effect. Automatic downgrade is allowed because no material unknown exploit leverage remains. 5. One-sentence report phrase GVE ring reset leaks posted AF_XDP zero-copy buffers, potentially depleting the affected queue without evidence of memory corruption or broader host compromise. 6. Manual review advice NO MANUAL CHECK NEEDED The patch fully identifies a constrained resource leak, and no Important-preserving primitive is present. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: gve: fix XSK buffer leak when rings are stopped Commit: 506f9de069d07a72b9887ce3edd2fdf32f4953aa Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=506f9de069d07a72b9887ce3edd2fdf32f4953aa Commit description: GVE does not free XSK buffers when resetting ring state as a part of stopping queues. This causes all XSK buffers which are posted to the NIC to be leaked. Free XSK buffers attached to an allocated buf_state when stopping rings. This issue was hit in production. Fixes: c1fffc5 ("gve: implement DQO RX datapath and control path for AF_XDP zero-copy") Cc: stable@vger.kernel.org Reviewed-by: Tim Hostetler Reviewed-by: Jordan Rhee Signed-off-by: Joshua Washington Link: https://patch.msgid.link/20260930214735.3288780-2-joshwash@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: drivers/net/ethernet/google/gve/gve_rx_dqo.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=506f9de069d07a72b9887ce3edd2fdf32f4953aa ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99047 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99047 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:H/PR:L/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS score: 3.3 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: unknown Paranoid ActionableScore: 1 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).