From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45880][LOW] PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails [ Upstream Date: Wed, 27 May 2026 23:22:15 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45880 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: 0 X-AL-KERNEL-Commit: baa42b756d183a59572f3890981a3d32b8d05d40 List-Id: CVE: CVE-2026-45880 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails [ Upstream Commit: baa42b756d183a59572f3890981a3d32b8d05d40 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=baa42b756d183a59572f3890981a3d32b8d05d40 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45880 Analysis date: Wed, 27 May 2026 23:22:15 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A PCI P2PDMA mmap error path can leak a `pgmap` per-CPU reference when `vm_insert_page()` fails, causing later PCI device removal to hang. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45880 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45880 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-2026-45880 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-772;CWE-404;**CWE-400;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'PCI P2PDMA p2pmem_alloc_mmap can leak a pgmap per CPU reference when vm_insert_page() fails after P2P memory allocation. The leaked reference can make memunmap_pages() wait indefinitely during PCI device removal, causing a local device teardown denial of service. For the CVSS the PR:L is used in the paranoid score because delegated access to the PCI P2PDMA sysfs mmap interface or device management may exist in some deployments, while normal reliable triggering usually requires privileged PCI or device access. The issue is not network reachable. Impact is availability only through stuck cleanup or device removal. No supported evidence indicates information disclosure, integrity impact, kernel memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) MAYBE READ SIMPLEFIX HARDWARE DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown * Availability impact realistic: +1 A leaked `pgmap` per-CPU reference can make `memunmap_pages()` wait indefinitely during PCI device removal. * Local delegated device access: +1 in paranoid scoring Some deployments may expose PCI P2PDMA sysfs mmap or device-management paths to a service account or delegated operator. * Requires privileged PCI/device-management access in typical deployments: -2 conservative Reliable triggering normally requires access to P2PDMA sysfs mmap plus a later PCI device removal path. * Hard failure condition required: -1 The leak only occurs if `vm_insert_page()` fails after P2P memory allocation. * Rare/configuration-specific subsystem: -1 conservative PCI P2PDMA is not a broad default userspace interface. * No memory corruption: +0 This is a missing `percpu_ref_put()` on an error path, not UAF, OOB write, arbitrary write, or heap corruption. ## 3. Reachability analysis The bug is reachable through `p2pmem_alloc_mmap()` when P2PDMA memory is mmaped and `vm_insert_page()` fails. Normal exploitation requires local access to the PCI P2PDMA sysfs mmap interface and a later device removal or teardown operation. In standard deployments this is privileged or tightly controlled. Namespaces and containers only matter if PCI/P2PDMA device access is explicitly delegated. The issue is not network reachable. ## 4. Severity interpretation This behaves like Low or ordinary Moderate. The realistic impact is local availability loss during PCI device teardown due to a leaked reference. There is no evidence of memory corruption, data disclosure, integrity impact, or privilege escalation. ## 5. One-sentence report phrase A PCI P2PDMA mmap error path can leak a `pgmap` per-CPU reference when `vm_insert_page()` fails, causing later PCI device removal to hang. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This is a local resource-reference leak in a niche PCI P2PDMA error path, with no demonstrated memory corruption, remote trigger, or privilege escalation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails [ Upstream Commit: baa42b756d183a59572f3890981a3d32b8d05d40 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=baa42b756d183a59572f3890981a3d32b8d05d40 Changed files: drivers/pci/p2pdma.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=baa42b756d183a59572f3890981a3d32b8d05d40 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45880 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45880 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:H/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 0 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).