From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80542][MODERATE REGULAR] drm/amd/display: Fix NULL pointer dereference in amdgpu_dm_crtc_set_vblank() Date: Wed, 26 Aug 2026 12:55:37 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80542 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: 3 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af List-Id: CVE: CVE-2026-80542 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: drm/amd/display: Fix NULL pointer dereference in amdgpu_dm_crtc_set_vblank() Commit: 5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80542 Analysis date: Wed, 26 Aug 2026 12:55:37 -0400 ActionableScore: 3 ActionableScore lower bound: unknown Actionable bucket: Borderline, manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80542 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80542 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-80542 MODERATE 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-754;*CWE-20;BEST CVSS score: '5.5';DESCR 'A NULL-pointer dereference in the AMDGPU display vblank path occurs because amdgpu_dm_crtc_set_vblank() can dereference acrtc_state stream before a stream is attached to the CRTC state. A local process with access to the DRM device can trigger this through DRM_IOCTL_MODE_CRTC_GET_SEQUENCE when vblank is enabled or queried at the wrong display state, causing a kernel crash (DoS). For the CVSS the PR:L is used because triggering requires local code execution and access to the DRM device node, but not full administrative privileges. The issue is not network reachable and is tied to local graphics control paths rather than packet or remote protocol input. Impact is denial of service only because the patch indicates a NULL dereference and does not show a UAF, OOB write, information leak, or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3) SKIP CVE-2026-80542 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER NULLPTR SIMPLEFIX HARDWARE TEST - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 1. ActionableScore * Conservative score: 3 * Paranoid score: 3 * Final recommended bucket: **Borderline, manual review recommended**:: 2. Signal breakdown * Local unprivileged trigger: +1. A local process with access to the DRM device node can reach `DRM_IOCTL_MODE_CRTC_GET_SEQUENCE`. * Reliable kernel crash / strong DoS: +1. The commit shows a concrete NULL pointer dereference and kernel crash path. * Broad/default/common subsystem or broadly deployed exposure: +1. AMDGPU DRM is a common local graphics stack path on affected systems. * No generic memory corruption bonus. The patch shows a NULL dereference, not UAF, OOB write, type confusion, refcount misuse, or attacker-controlled overwrite. * No privilege escalation bonus. There is no supported LPE primitive. * No network reachability bonus. This is a local DRM ioctl path. 3. Reachability analysis The bug is triggered locally through DRM ioctl access, specifically via the vblank sequence query path before `acrtc_state->stream` is attached. Typical desktop or GPU compute systems may allow non-root users access to DRM device nodes through local seat/session permissions or render/video groups, so PR:L is the practical CVSS interpretation. Containers usually do not get direct DRM device access unless explicitly passed through. The path is not network reachable and requires affected AMDGPU display hardware and driver state. 4. Severity interpretation This behaves like an actionable local DoS rather than an Important-class vulnerability. The demonstrated impact is a kernel NULL pointer dereference and crash. Theoretical escalation is not supported because the patch does not indicate UAF, stale object reuse, writable corruption, callback control, or an arbitrary read/write primitive. It should not be auto-promoted to memory corruption, but the local unprivileged DRM ioctl reachability makes manual triage reasonable. 5. One-sentence report phrase A local NULL-pointer dereference in the AMDGPU display vblank path can be triggered through DRM_IOCTL_MODE_CRTC_GET_SEQUENCE before a stream is attached to the CRTC state, causing a kernel crash (DoS) without evidence of privilege escalation. 6. Manual review recommendation MANUAL CHECK RECOMMENDED. Reason: local DRM ioctl reachability and kernel crash are concrete, but the bug is NULL dereference only and does not show a memory corruption or LPE primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amd/display: Fix NULL pointer dereference in amdgpu_dm_crtc_set_vblank() Commit: 5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af Commit description: amdgpu_dm_crtc_set_vblank() dereferences acrtc_state->stream when vblank is enabled/queried from DRM_IOCTL_MODE_CRTC_GET_SEQUENCE before a stream is attached to it. BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: amdgpu_dm_crtc_set_vblank+0x6b/0x4d0 [amdgpu] Call Trace: drm_vblank_enable drm_vblank_get drm_crtc_get_sequence_ioctl drm_ioctl_kernel drm_ioctl Reproduced by running VKCTS with WSI tests enabled on RADV. Guard the enable path on acrtc_state->stream being non-NULL, matching the existing checks in this function. Fixes: 34d66bc ("drm/amd/display: Fix Xorg desktop unresponsive on Replay panel") Reviewed-by: Melissa Wen Signed-off-by: Samuel Pitoiset Signed-off-by: Alex Deucher (cherry picked from commit 7b1b31b ) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.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=5045fb4c70bfde36a05e0f41cf35ddfb6d85d3af ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80542 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80542 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: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: unknown Paranoid ActionableScore: 3 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).