From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64097][MODERATE REGULAR] drm/amd/display: Validate GPIO pin LUT table size before iterating Date: Sun, 19 Jul 2026 20:43:01 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64097 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: 9900f6954be779011e7c2cd42addd87baf028bc5 List-Id: CVE: CVE-2026-64097 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/amd/display: Validate GPIO pin LUT table size before iterating Commit: 9900f6954be779011e7c2cd42addd87baf028bc5 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9900f6954be779011e7c2cd42addd87baf028bc5 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64097 Analysis date: Sun, 19 Jul 2026 20:43:01 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A malformed AMD VBIOS GPIO pin LUT table can cause the display BIOS parser to read past the mapped BIOS image, with realistic impact limited to driver failure or kernel DoS and only limited paranoid confidentiality concern. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64097 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64097 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: MODERATE REGULAR 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-2026-64097 MODERATE 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:H/UI:N/S:U/C:L/I:N/A:H';CWE-125;CWE-130;*CWE-20;CWE-125;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'The AMD display VBIOS GPIO pin LUT parser derives the number of gpio_pin entries from the table structuresize field and can iterate past the mapped BIOS image when that size is larger than the accessible data. This is an out of bounds read in kernel firmware parsing and can be reached with a malformed or attacker controlled VBIOS image. For the CVSS the PR:H is used because reliable exploitation normally requires control over GPU firmware, a malicious device image, or another administrative firmware path on the target. The issue is not network reachable and is not triggered by normal packet or remote input traffic. Impact is primarily denial of service through driver failure or a kernel fault. A limited confidentiality impact is kept only in the paranoid score because the primitive is an OOB read, but there is no clear write primitive or privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) SKIP CVE-2026-64097 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE OOB HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_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 Conservative signals: * Firmware-mediated external influence: +1. The malformed input is a VBIOS GPIO pin LUT table, so attacker influence normally requires control over firmware, a device image, or an equivalent trusted firmware path. * Availability impact realistic: +1. The parser can read beyond the mapped BIOS image, which can plausibly cause driver failure or a kernel fault. * Requires admin/root/firmware control in typical deployments: -2. Reliable triggering normally requires privileged control over GPU firmware or hardware-provided VBIOS data. Paranoid additions: * Confidentiality impact plausible: +1. The primitive is an OOB read in kernel firmware parsing, so limited unintended kernel read impact is technically possible, although no user-visible disclosure path is shown. * Broad/common subsystem exposure: +1. AMDGPU display code is broadly deployed on affected AMD GPU systems, but the attacker-controlled VBIOS precondition keeps this from being broadly reachable. Not counted: * No generic memory corruption score. The patch shows an OOB read only, not OOB write, UAF, double free, type confusion, or refcount corruption. * No privilege escalation score. There is no demonstrated reclaim, write primitive, callback control, or object confusion. * No remote reachable score. This is not triggered by packets or a network protocol. ## 3. Reachability analysis The bug is reachable during AMD display VBIOS parsing when the GPIO pin LUT table reports a `structuresize` larger than the actually accessible BIOS image data. A normal local unprivileged user is not expected to control this input. Practical triggering usually requires a malicious or corrupted VBIOS, a malicious device, firmware replacement, or an administrative firmware-loading path. Namespaces and containers do not materially reduce the privilege requirement because the relevant input is firmware or device-provided data, not an ordinary namespaced userspace API. Call-site confidence: high for the shown parser behavior, medium for final runtime impact because no crash trace or disclosure path is included. ## 4. Severity interpretation This behaves more like a Low-like or ordinary Moderate firmware-fed OOB read than an Important kernel vulnerability. The theoretical risk is limited confidentiality impact or crash from reading past the BIOS image. Realistic exploitation evidence is weak because there is no write primitive, no memory lifetime issue, no privilege escalation path, and no normal remote or unprivileged trigger. ## 5. One-sentence report phrase A malformed AMD VBIOS GPIO pin LUT table can cause the display BIOS parser to read past the mapped BIOS image, with realistic impact limited to driver failure or kernel DoS and only limited paranoid confidentiality concern. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Manual review is useful because this is a kernel OOB read from firmware-controlled data, but the low reachability and lack of write or LPE primitive make it unsuitable for Important-class handling without additional evidence. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amd/display: Validate GPIO pin LUT table size before iterating Commit: 9900f6954be779011e7c2cd42addd87baf028bc5 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9900f6954be779011e7c2cd42addd87baf028bc5 Commit description: [Why&How] The GPIO pin table parsers in get_gpio_i2c_info() and bios_parser_get_gpio_pin_info() derive an element count from the VBIOS table_header.structuresize field, then iterate over gpio_pin[] entries. However, GET_IMAGE() only validates that the table header itself fits within the BIOS image. If the VBIOS reports a structuresize larger than the actual mapped data, the loop reads past the end of the BIOS image, causing an out-of-bounds read. Fix this by calling bios_get_image() to validate that the full claimed structuresize is accessible within the BIOS image before entering the loop in both functions. Assisted-by: GitHub Copilot:claude-opus-4-6 Reviewed-by: Alex Hung Signed-off-by: Harry Wentland Signed-off-by: Ivan Lipski Tested-by: Dan Wheeler Signed-off-by: Alex Deucher (cherry picked from commit ba5e95b ) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/display/dc/bios/bios_parser2.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=9900f6954be779011e7c2cd42addd87baf028bc5 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64097 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64097 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:H/UI:N/S:U/C:L/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: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).