From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-99257][LOW] gpio: shared: gracefully handle no-device lookup of shared GPIOs Date: Tue, 03 Nov 2026 22:46:56 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-99257 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: 7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 List-Id: CVE: CVE-2026-99257 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: gpio: shared: gracefully handle no-device lookup of shared GPIOs Commit: 7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99257 Analysis date: Tue, 03 Nov 2026 22:46:56 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A device-less shared-GPIO fwnode lookup can dereference a NULL consumer and crash the kernel, with no demonstrated memory-corruption or authorization primitive. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99257 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99257 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-2026-99257 LOW https://www.kernelcve.org/list/?q=CVE-2026-99257 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both 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-476;*CWE-20;CWE-754;BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference occurs in gpio_shared_add_proxy_lookup because dev_name is called with a NULL consumer during a fwnode based shared GPIO lookup that has no associated struct device. The demonstrated primitive is a NULL dereference and possible kernel crash rather than UAF or controllable memory corruption. For the CVSS the PR:L value represents the conservative case where a local user can indirectly activate an affected driver path. Exploitation also requires a specific shared GPIO platform configuration and a caller that performs the unsupported no device lookup. There is no direct network attack path and no supported confidentiality or integrity impact. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. 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 LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE SIMPLEFIX LEAK HARDWARE LINUS - - 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 * Raw paranoid score: 1 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate**:: No floor or cap applies. 2. Signal breakdown * +1 Reliable kernel crash/DoS: `dev_name(consumer)` receives a confirmed NULL `consumer`, plausibly causing a kernel NULL-pointer fault. * No negative adjustment: the shared-GPIO/platform configuration is specialized, but the evidence does not prove it is both rare and attacker-inaccessible. * No memory-corruption points: the patch shows no OOB write, UAF, stale object, refcount mutation, or attacker-controlled overwrite. * No reachability point: no attacker-accessible caller or complete local-user trigger is supplied. * No authorization point: the new NULL check validates an unsupported lookup mode; it does not restore a capability, credential, ownership, or other DENY-to-ALLOW security guard. * No confidentiality or integrity impact is shown. The possible crash is not counted again as a separate availability signal. 3. Reachability analysis The affected operation requires a shared-GPIO platform lookup and a fwnode-based lookup without an associated `struct device`. The supplied patch does not identify who can invoke the relevant caller, whether userspace can induce it, or whether host administration or prior platform configuration is required. Accordingly, host-admin and UID-0 requirements remain unknown. No namespace-scoped capability path, remote path, special physical attack, or timing race is established. 4. Primitive and severity reading The exact primitive is a NULL-pointer dereference through `dev_name(NULL)`. This is an invalid dereference, not active structured-state corruption or a lifetime violation, so it is CLASS_C. The supported consequence is a possible kernel fault/DoS; no useful primitive remains after excluding that crash. B5-R does not apply because there is no heap OOB write, retry-accumulated index, or later consumption of corrupted state. B3-PENDING and B4-PENDING also do not apply. ImportantCandidate is therefore NO, and automatic downgrade is safe. 5. One-sentence report phrase A device-less shared-GPIO fwnode lookup can dereference a NULL consumer and crash the kernel, with no demonstrated memory-corruption or authorization primitive. 6. Manual review advice NO MANUAL CHECK NEEDED The patch establishes only a straightforward unsupported-input NULL dereference. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: gpio: shared: gracefully handle no-device lookup of shared GPIOs Commit: 7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 Commit description: We use platform lookup tables for shared GPIOs. This mechanism needs a struct device to work so fwnode-based lookup with no device associated currently causes a NULL-pointer deference. Adding this functionality will require a larger rework and it has never worked anyway so add a check that allows the kernel to gracefully handle this situation with an error ahead of implementing that functionality as a new feature. Cc: stable@vger.kernel.org Reported-by: Abel Vesa Fixes: a060b8c ("gpiolib: implement low-level, shared GPIO support") Link: https://patch.msgid.link/20261014-gpio-shared-fwnode-lookup-v4-2-2253ad645fd6@oss.qualcomm.com Signed-off-by: Bartosz Golaszewski Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpio/gpiolib-shared.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=7f9eb6aaf9a3ab7fa2b7dcc38660c27db12d4ec1 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-99257 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99257 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: Not available 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: 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).