From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97948][LOW] powerpc/eeh: Fix recursive locking on devices without EEH sensitive driver Date: Sat, 26 Sep 2026 15:34:08 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97948 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: 0 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 102e3dc5ab5ba052e294819e83384166b242c1ec List-Id: CVE: CVE-2026-97948 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: powerpc/eeh: Fix recursive locking on devices without EEH sensitive driver Commit: 102e3dc5ab5ba052e294819e83384166b242c1ec Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=102e3dc5ab5ba052e294819e83384166b242c1ec Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97948 Analysis date: Sat, 26 Sep 2026 15:34:08 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A recursive locking flaw in the PowerPC EEH device recovery path can deadlock the eehd thread and prevent recovery or removal of an affected PCI device, with no demonstrated memory-corruption or privilege-escalation impact. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97948 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97948 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-2026-97948 LOW https://www.kernelcve.org/list/?q=CVE-2026-97948 CHECK WITH IMPACT FROM ORIG NN LOW 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-833;CWE-667;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A recursive locking flaw in the PowerPC EEH recovery path can deadlock the eehd thread when eeh_rmv_device attempts to acquire pci_rescan_remove_lock while the same lock is already held by eeh_handle_normal_event. The condition requires a specific PCI error recovery path involving a PHB error or an affected device whose driver requests reset without EEH recovery handlers. This can prevent recovery or removal of the affected PCI device and cause denial of service for dependent hardware functions. For the CVSS the PR:L value is used for the paranoid score because a local user or service with access to an affected PCIe device may be able to influence device error or recovery conditions in some deployments. The issue is not directly network reachable. No memory corruption, information disclosure, integrity impact, or privilege escalation primitive is shown by the patch.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) YES LOCK HARDWARE LINUS YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES ## 1. ActionableScore * Raw conservative score: -2 * Conservative score: 0 after lower-bound normalization * Raw paranoid score: -2 * Paranoid score: 0 after lower-bound normalization * Final recommended bucket: **Ordinary Moderate**:: No conservative or paranoid escalation is justified. The supplied patch establishes a recursive mutex acquisition and an EEH recovery-thread deadlock, not memory corruption, an ownership violation, a security-boundary bypass, or a privilege-escalation primitive. ## 2. Signal breakdown * -2 Physical-only or rare hardware-specific prerequisite. The affected path is specific to PowerPC EEH-capable systems and requires an EEH/PHB error recovery event or a PCI device driver returning `PCI_ERS_RESULT_NEED_RESET` without EEH-sensitive recovery handlers. * +0 Reliable host-wide crash or strong DoS. Not awarded. The demonstrated result is that the `eehd` kernel thread blocks on `pci_rescan_remove_lock`; the patch does not establish a host panic, general kernel hang, filesystem failure, or system-wide outage. * +0 Availability impact beyond the immediate affected device. Not awarded. The visible impact is failure to recover or remove the affected PCI device. Broader loss of availability depends on what device is affected and is not established. * +0 Remote reachability. Not awarded. No network-controlled input path is shown. * +0 Local unprivileged trigger. Not awarded. The supplied evidence does not establish that an ordinary user can generate the required EEH event or drive the complete recovery path. * +0 Memory corruption or lifetime primitive. Not awarded. There is no UAF, double free, stale pointer dereference, refcount mutation, OOB access, arbitrary write, or controlled object replacement. * +0 Confidentiality or integrity impact. Not awarded. No disclosure, unauthorized modification, authorization bypass, or privilege escalation mechanism is established. The unbounded arithmetic is -2. The ActionableScore is normalized to the minimum score of 0. ## 3. Reachability analysis The triggering condition is an EEH recovery path on PowerPC hardware. It requires either an error detected directly on the PHB or a device error path where `error_detected()` returns `PCI_ERS_RESULT_NEED_RESET` for a driver that lacks EEH-sensitive handlers such as `slot_reset()` and `resume()`. The patch does not identify the actor capable of inducing the relevant hardware or PCI recovery event. It therefore does not establish that host administrator privileges are required, but it also does not establish below-host-admin reachability. `HostAdminRequired=UNKNOWN` is appropriate. There is no shown namespace-aware interface, no demonstrated attacker-created namespace path, and no evidence that the complete trigger can be performed with namespace-scoped privileges. `NamespaceScopedPrivilege=UNKNOWN` is appropriate. The issue is not directly network reachable. Firmware, PCIe hardware, device faults, or device-specific recovery conditions are material prerequisites. ## 4. Primitive and severity interpretation The exact primitive is a recursive acquisition of `pci_rescan_remove_lock`: `eeh_handle_normal_event()` holds the lock -> `eeh_reset_device()` is called -> `eeh_rmv_device()` attempts to acquire the same lock again -> `eehd` blocks on its own lock. This is a synchronization and availability defect, classified as `CLASS_C`. It is not an active structured-object lifetime violation and does not involve fixed stale storage, UAF, refcount corruption, repeated release, object reuse, or post-free field consumption. The demonstrated consequence is an EEH recovery-thread deadlock that can prevent recovery or hot removal of the affected PCI device. A broader host-level denial of service is speculative because the patch does not establish that the affected device must be critical to system operation. `ImportantCandidate=NO` because no meaningful exploitation leverage beyond the device recovery failure is unresolved. `AutoDowngradeAllowed=YES` because the issue has no demonstrated kernel corruption, lifetime primitive, authorization bypass, protected-resource access, or cross-boundary effect. ## 5. One-sentence report phrase A recursive locking flaw in the PowerPC EEH device recovery path can deadlock the eehd thread and prevent recovery or removal of an affected PCI device, with no demonstrated memory-corruption or privilege-escalation impact. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED The patch demonstrates a hardware-specific recursive-lock deadlock with device recovery impact only. No concrete corruption, security-boundary, or below-privilege attacker path is established. ## 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: powerpc/eeh: Fix recursive locking on devices without EEH sensitive driver Commit: 102e3dc5ab5ba052e294819e83384166b242c1ec Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=102e3dc5ab5ba052e294819e83384166b242c1ec Commit description: The commit 1010b4c ("powerpc/eeh: Make EEH driver device hotplug safe") refactored the EEH code such that the pci_rescan_remove_lock is held at the beginning of eeh_handle_normal_event() and the eeh_reset_device() is called with that lock being held. Looks like the commit missed to remove the existing lock/unlock inside eeh_rmv_device() which is no longer necessary. This is causing the eehd to hang on the lock which it actually holds when that code path is taken. [<0>] 0xc00000011c78f870 [<0>] __switch_to+0xfc/0x1a0 [<0>] pci_lock_rescan_remove+0x30/0x44 [<0>] eeh_rmv_device+0x290/0x2e0 [<0>] eeh_pe_dev_traverse+0x80/0x130 [<0>] eeh_reset_device+0xcc/0x23c [<0>] eeh_handle_normal_event+0x830/0xa80 [<0>] eeh_event_handler+0xf8/0x190 [<0>] kthread+0x194/0x1b0 [<0>] start_kernel_thread+0x14/0x18 The issue is seen for cases where the errors are detected on the PHB directly AND|OR for devices where the driver error_detected() returns PCI_ERS_RESULT_NEED_RESET, and driver being not EEH sensitive(i.e no error handlers like slot_reset(), resume() etc defined). Fixes: 1010b4c ("powerpc/eeh: Make EEH driver device hotplug safe") Cc: stable Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Shivaprasad G Bhat Reviewed-by: Amit Machhiwal Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/178404937381.913.2759874335293830160.stgit@linux.ibm.com Signed-off-by: Greg Kroah-Hartman Changed files: arch/powerpc/kernel/eeh_driver.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=102e3dc5ab5ba052e294819e83384166b242c1ec ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97948 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97948 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: unknown Paranoid ActionableScore: 0 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).