From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-90411][LOW] nvme-fc: unmap cmd_iu DMA on rsp_iu mapping failure in init_request [ Upstream Date: Fri, 18 Sep 2026 08:00:26 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-90411 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: 2 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: c0892cfb60a75e2c86ba8e2127b133f6549c12b3 List-Id: CVE: CVE-2026-90411 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: nvme-fc: unmap cmd_iu DMA on rsp_iu mapping failure in init_request [ Upstream Commit: c0892cfb60a75e2c86ba8e2127b133f6549c12b3 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c0892cfb60a75e2c86ba8e2127b133f6549c12b3 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90411 Analysis date: Fri, 18 Sep 2026 08:00:26 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90411 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90411 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-2026-90411 LOW https://www.kernelcve.org/list/?q=CVE-2026-90411 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-772;*CWE-401;CWE-404;Other CVSS 'AV:A/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.8';DESCR 'A DMA mapping leak in the NVMe FC host path can occur when __nvme_fc_init_request() maps cmd_iu successfully and then fails to map rsp_iu. Because blk-mq does not call exit_request() after init_request() failure, the cmd_iu DMA mapping can remain leaked for each failed request initialization. The issue is primarily a resource leak and does not show a direct UAF, OOB access, arbitrary write, or information leak primitive. For the CVSS the PR:L is used in the paranoid score because some deployments may delegate NVMe FC management or recovery operations to a service account or reduced capability administrator. The attack surface is adjacent to the storage fabric rather than public Internet reachable, and reliable triggering depends on DMA mapping failure or resource pressure, so AC:H is appropriate. Impact is denial of service through possible DMA or IOMMU resource exhaustion, not privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) YES SIMPLEFIX NVME LEAK ERRORPATH DMAorINTERRUPT LINUS MEMORY DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 2 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap was applied. The paranoid score is higher because repeated rsp_iu DMA mapping failures can plausibly accumulate leaked cmd_iu DMA mappings and cause DMA or IOMMU resource pressure. 2. Signal breakdown Positive signals: * +1 Concrete persistent kernel resource/reference leak. The patch establishes that cmd_iu is DMA mapped, rsp_iu mapping may fail, and blk-mq will not call exit_request() after init_request() failure, so the cmd_iu DMA mapping is leaked. * +1 Paranoid sustained resource exhaustion. The commit states the leak happens for every op whose rsp_iu mapping fails, so repeated failures could plausibly exhaust DMA/IOMMU resources or degrade NVMe-FC operation. Negative or non-awarded signals: * RealUAF not awarded. The bug is a missing DMA unmap on an error path, not a stale post-free object use. * Concrete repeated release/refcount not awarded. There is no first release followed by a second lifetime mutation on the same dangling reference. * Controlled reclaim not demonstrated. * Arbitrary write not demonstrated. * Confidentiality and integrity not awarded. The evidence supports a resource leak, not disclosure or unauthorized modification of protected state. * Reliable kernel crash not awarded conservatively. Resource exhaustion is plausible, but an immediate host-wide crash from one or few operations is not established. * Remote reachability not awarded. NVMe-FC involves a storage fabric, but the vulnerable event is a local host DMA mapping failure during request initialization, not direct attacker packet processing. * Host-admin penalty not applied because the supplied evidence does not fully resolve the external control path. However, no local unprivileged bonus is awarded either. * Race/timing penalty not applied. This is an ordered error-path cleanup bug, not a timing race. 3. Reachability analysis The vulnerable path is in the NVMe-FC host driver during __nvme_fc_init_request(). Triggering requires cmd_iu DMA mapping to succeed and rsp_iu DMA mapping to fail. That failure condition usually depends on DMA/IOMMU mapping failure or resource pressure. The complete attacker model is not fully established from the supplied patch. Managing NVMe-FC controllers and recovery paths is commonly administrative or service-managed, but the evidence provided does not conclusively prove host-admin-equivalent privilege for every possible deployment. Therefore HostAdminRequired is UNKNOWN rather than YES. This is not clearly namespace-scoped. NVMe-FC is a host storage transport path, and no evidence shows that an attacker-created namespace can perform the complete controller setup, request initialization, failure induction, and cleanup sequence. NamespaceScopedPrivilege is UNKNOWN. There is no public Internet network trigger established. The relevant exposure is adjacent to storage-fabric operation, not generic remote TCP packet handling. No special rare hardware penalty is applied because NVMe-FC is specialized but not enough by itself to subtract points under the supplied rules. 4. Primitive and severity interpretation The exact primitive is a persistent DMA mapping leak on an init_request error path. cmd_iu is mapped for DMA, rsp_iu mapping fails, and without the patch the already mapped cmd_iu is not unmapped. This is fixed stale resource ownership, not active structured object UAF. There is no evidence of object reuse, controlled replacement, arbitrary read/write, callback influence, refcount takeover, or privilege escalation. The demonstrated consequence is resource leakage. The plausible worst case is denial of service through DMA/IOMMU resource exhaustion after repeated failures. The speculative consequence would be broader host instability under sustained resource pressure, but no memory corruption or LPE primitive is supported. PrimitiveClass is CLASS_C because the established behavior is resource leak / DoS-oriented without an independently useful corruption primitive. ImportantCandidate is NO because no Class A or strong Class B primitive is established. AutoDowngradeAllowed is YES because this is a constrained resource-leak issue without unresolved memory-corruption, authorization-bypass, or lifetime-mutation leverage. 5. One-sentence report phrase A DMA mapping leak in the NVMe-FC host init_request error path can leave cmd_iu mappings unreleased when rsp_iu mapping fails, allowing repeated failures to cause DMA or IOMMU resource exhaustion and denial of service. 6. Manual review recommendation NO MANUAL CHECK NEEDED This is a concrete resource leak, but it does not establish UAF, double release, arbitrary write, information disclosure, authorization bypass, or privilege escalation. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: nvme-fc: unmap cmd_iu DMA on rsp_iu mapping failure in init_request [ Upstream Commit: c0892cfb60a75e2c86ba8e2127b133f6549c12b3 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c0892cfb60a75e2c86ba8e2127b133f6549c12b3 Changed files: drivers/nvme/host/fc.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=c0892cfb60a75e2c86ba8e2127b133f6549c12b3 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90411 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90411 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:A/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.8 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: 1 Paranoid ActionableScore: 2 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).