From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46268][LOW] PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition [ Upstream Date: Wed, 03 Jun 2026 15:59:50 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46268 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: eb9aa9f8010465d927864f5a35bdc5604b0ff51a List-Id: CVE: CVE-2026-46268 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition [ Upstream Commit: eb9aa9f8010465d927864f5a35bdc5604b0ff51a Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb9aa9f8010465d927864f5a35bdc5604b0ff51a Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46268 Analysis date: Wed, 03 Jun 2026 15:59:50 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46268 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46268 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-2026-46268 LOW CHECK 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:H';CWE-617;CWE-703;CWE-754;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'p2pmem_alloc_mmap() used an inverted VM warning condition after P2PDMA pages changed to an initial refcount of zero. A local caller that can reach the p2pmem mmap path can trigger a false CONFIG_DEBUG_VM warning on the expected zero refcount before the code sets the page count and inserts the page into the VMA. For the CVSS the PR:L is used in the paranoid score because a local process with permission to mmap the exposed p2pmem interface may be enough, although typical deployments restrict this path to administrative users. The issue is not network reachable. Impact is mainly a warning and at worst denial of service if panic_on_warn or similar debug policy turns the warning into a kernel panic.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) MAYBE READ WARNONLY SIMPLEFIX HARDWARE INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - 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 * Reliable kernel crash / strong DoS: +1 only in paranoid interpretation. The warning can become a panic if CONFIG_DEBUG_VM and panic_on_warn or similar policy are enabled. * Local unprivileged trigger: +1 only in paranoid interpretation. This assumes a local process has permission to mmap the exposed p2pmem interface. * Requires admin/root/CAP level access in typical deployments: -2 for conservative scoring. Access to PCI P2PDMA p2pmem is normally not broadly available to unprivileged users. * Rare and difficult-to-reach subsystem/configuration: -1 to -2. P2PDMA requires suitable PCI peer-to-peer memory hardware and the visible impact depends on debug warning behavior. * No generic memory corruption signal. The patch flips a VM_WARN_ON_ONCE_PAGE condition before set_page_count() and vm_insert_page(). It does not show UAF, double-free, OOB write, arbitrary write, or page-cache corruption. 3. Reachability analysis The path is local and requires reaching p2pmem_alloc_mmap(). In typical systems this requires specialized PCI P2PDMA hardware and privileged or explicitly delegated access to the p2pmem interface. It is not network reachable and not a common default attack surface. Namespaces or containers do not normally make this path available unless the device node or related file interface is intentionally passed through. Realistic exploitation is mainly triggering a false warning, with DoS only if the system is configured to panic on warnings. 4. Severity interpretation This behaves like a Low-like or ordinary Moderate issue, not an Important-class vulnerability. The theoretical worst case is local DoS through warning-to-panic behavior under debug or strict panic policy. There is no realistic evidence of confidentiality impact, integrity impact, privilege escalation, or memory corruption from the patch context. 5. One-sentence report phrase An inverted VM warning condition in p2pmem_alloc_mmap() can cause a false CONFIG_DEBUG_VM warning for the expected zero refcount of a newly allocated P2PDMA page, and at worst may cause local DoS on systems configured to panic on warnings. 6. Manual review recommendation NO MANUAL CHECK NEEDED. The issue is a false warning condition in a specialized PCI/P2PDMA path, with no supported memory corruption or privilege escalation primitive, and can be handled as low-priority unless the environment widely exposes p2pmem mmap with panic_on_warn enabled. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition [ Upstream Commit: eb9aa9f8010465d927864f5a35bdc5604b0ff51a Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb9aa9f8010465d927864f5a35bdc5604b0ff51a 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=eb9aa9f8010465d927864f5a35bdc5604b0ff51a ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46268 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46268 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: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:H The Best / paranoid CVSS score: 5.5 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).