From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74732][LOW] drm/amd/display: Check for tg ops in dce110_set_avmute [ Upstream Date: Sat, 22 Aug 2026 13:37:47 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74732 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: 0 X-AL-KERNEL-Commit: 853c2d31408bd45dcf92d0eb1f06eb439a56cf04 List-Id: CVE: CVE-2026-74732 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/amd/display: Check for tg ops in dce110_set_avmute [ Upstream Commit: 853c2d31408bd45dcf92d0eb1f06eb439a56cf04 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=853c2d31408bd45dcf92d0eb1f06eb439a56cf04 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74732 Analysis date: Sat, 22 Aug 2026 13:37:47 -0400 ActionableScore: 1 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A hardware-specific NULL pointer dereference in drm/amd/display dce110_set_avmute() can crash affected Southern Islands AMD dGPU systems when HDMI display mute or power-off handling calls missing timing generator ops. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74732 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74732 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-2026-74732 LOW CHECK WITH IMPACT FROM ORIG NN MODERATE 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-476;CWE-703;CWE-754;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference can occur in the AMD display dce110_set_avmute() path because older DCE timing generators may not provide tg funcs is_tg_enabled or wait_for_state. A local user on an affected Southern Islands AMD dGPU system can potentially trigger the bug by causing the HDMI display to be turned off or muted, which may crash the kernel or break the graphics stack. For the CVSS the PR:L value is used because a local user with an active graphics session may be able to trigger display power or mode changes, while full administrator privileges are not necessarily required. The issue is not network reachable and depends on affected AMD DCE hardware and the HDMI display path. Impact is denial of service with A:H. No direct confidentiality or integrity impact is supported by the code change.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) SKIP CVE-2026-74732 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER NULLPTR SIMPLEFIX HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 1 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Conservative signals: * Local unprivileged trigger: +1. A local desktop user with an active graphics session may be able to trigger display off or HDMI AV mute behavior without full administrator privileges. * Reliable kernel crash / strong DoS: +1. The commit explicitly describes a NULL pointer dereference when turning the HDMI display off on affected hardware. * Physical-only or rare hardware-only condition: -2. The issue depends on older AMD Southern Islands dGPUs and the HDMI display path. Paranoid additional signal: * Availability impact realistic: +1. On affected systems, the NULL dereference may cause a kernel crash or unusable graphics stack from a relatively ordinary display power transition. Not applied: * Generic memory corruption: +0. This is a NULL function pointer dereference, not UAF, OOB write, double free, type confusion, or controlled overwrite. * Privilege escalation plausible: +0. No reclaim, stale object reuse, writable corruption sink, callback control, or object replacement is shown. * Remote reachable: +0. The affected path is local display control, not network reachable. * Confidentiality or integrity impact: +0. The patch supports DoS only. ## 3. Reachability analysis The bug is reachable only on systems with affected older AMD DCE timing generator hardware, specifically Southern Islands dGPUs using the HDMI path. A local user may plausibly trigger it through display power management, display off, or session driven HDMI state changes. Administrator privileges are not necessarily required if the user controls the graphical session, so PR:L is more appropriate than PR:H for CVSS style reasoning. Namespaces and containers do not materially improve reachability unless they have access to the host DRM device and display stack, which is uncommon for ordinary containers. The path is not remotely reachable and is not a packet processing or network protocol path. Call-site confidence: high, because the changed function and dereferenced function pointers are shown directly in the patch. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like hardware-specific DoS. The theoretical bug class is a NULL pointer dereference, but the realistic evidence supports only crash or graphics stack failure on specific AMD hardware. There is no supported memory corruption primitive and no practical privilege escalation path. ## 5. One-sentence report phrase A hardware-specific NULL pointer dereference in drm/amd/display dce110_set_avmute() can crash affected Southern Islands AMD dGPU systems when HDMI display mute or power-off handling calls missing timing generator ops. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can be auto-closed or deprioritized in most triage flows because it is a local, hardware-specific NULL pointer dereference DoS with no evidence of memory corruption, privilege escalation, confidentiality impact, integrity impact, or network reachability. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amd/display: Check for tg ops in dce110_set_avmute [ Upstream Commit: 853c2d31408bd45dcf92d0eb1f06eb439a56cf04 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=853c2d31408bd45dcf92d0eb1f06eb439a56cf04 Changed files: drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.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=853c2d31408bd45dcf92d0eb1f06eb439a56cf04 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74732 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74732 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:L/UI:N/S:U/C:N/I:N/A:H 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: 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).