From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-89828][LOW] drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init() Date: Wed, 16 Sep 2026 12:57:01 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-89828 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: e184e46ca1ba652ab8053a10a51b39aad06d3f5c List-Id: CVE: CVE-2026-89828 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init() Commit: e184e46ca1ba652ab8053a10a51b39aad06d3f5c Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e184e46ca1ba652ab8053a10a51b39aad06d3f5c Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89828 Analysis date: Wed, 16 Sep 2026 12:57:01 -0400 ActionableScore: 0 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A NULL pointer dereference in the amdgpu VRAM manager initialization error path can panic the kernel if cgroup region registration fails before list and gpu buddy initialization, but reliable triggering appears to require host level driver management and no UAF, privilege escalation, or network reachable primitive is established. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-89828 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89828 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-2026-89828 LOW https://www.kernelcve.org/list/?q=CVE-2026-89828 CHECK WITH IMPACT FROM ORIG NN MODERATE 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-665;**CWE-476;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the amdgpu VRAM manager load error path because drmm_cgroup_register_region was called before the VRAM reservation lists and the gpu buddy allocator were initialized. If cgroup region registration fails, teardown can run through amdgpu_ttm_fini and amdgpu_vram_mgr_fini while reservations_pending, reserved_pages, or mm free_trees are still uninitialized, causing a kernel panic. For the CVSS the PR:L value is used in the paranoid score because a reduced local actor may be able to influence driver load, device probe, recovery, or memory pressure in some delegated environments, although normal reliable triggering usually needs administrative control over the GPU driver. The issue is not network reachable and is tied to a local module or device initialization failure. Impact is denial of service via kernel crash only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) SKIP CVE-2026-89828 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER INIT ERRORPATH HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=0 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=YES NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES ## 1. ActionableScore * Raw conservative score: -1 * Conservative score: 0 * Raw paranoid score: -1 * Paranoid score: 0 * Applied floor/cap: raw score clamped from -1 to 0 because ActionableScore is interpreted on a 0+ scale. * Final recommended bucket: **Ordinary Moderate**:: ## 2. Signal breakdown Positive signals: * +1 Reliable kernel crash / strong DoS: the commit explicitly states that the failure path can dereference NULL list pointers or NULL `free_trees`, resulting in kernel panic. * +0 Weak corruption concern: this is an invalid NULL dereference on an initialization error path, not a useful corruption primitive. Negative signals: * -2 Host-admin-equivalent trigger requirement: reliable triggering is tied to GPU driver module load, device probe, or equivalent host driver-management failure handling. The supplied evidence does not establish that an ordinary local user, DRM master, compositor, or container user can force the complete vulnerable sequence. Non-awarded signals: * RealUAF not awarded: no freed object or stale post-lifetime object use is established. * Concrete repeated release/refcount not awarded: no first release followed by a second lifetime mutation on the same dangling reference is shown. * Structured stale-object leverage not awarded: the stale state is uninitialized initialization state, and the demonstrated operation is NULL dereference during teardown. * Controlled reclaim not demonstrated. * Arbitrary write not demonstrated. * Confidentiality and integrity not awarded: no disclosure, ownership violation, controlled memory corruption, or privilege escalation primitive is supported. * Remote reachability not established. * Extra Availability not awarded because the same kernel panic is already counted once. ## 3. Reachability analysis The vulnerable path is reached when `drmm_cgroup_register_region()` fails during `amdgpu_vram_mgr_init()` before the VRAM manager lists and buddy allocator are initialized. Because `adev->mman.initialized` has already been set, teardown later calls `amdgpu_ttm_fini()` and `amdgpu_vram_mgr_fini()` against partially initialized state. Reliable attacker triggering appears to require host-level control over driver load, device probe, module reload, device binding, or an equivalent host GPU-management operation. The supplied context does not establish that an ordinary logged-in user, DRM master, compositor, display server, or delegated graphics service can force the complete failure path. Namespace-scoped reachability is not indicated. No direct network trigger exists. AMD GPUs are common hardware, but the vulnerable condition is a specific initialization failure path, not ordinary rendering or display use. Race repeatability is not relevant because this is an ordered initialization failure path, not a timing race. ## 4. Primitive and severity interpretation The exact primitive is a NULL pointer dereference during teardown after partial initialization. `reservations_pending` and `reserved_pages` may have zero-initialized `list_head` pointers, and `gpu_buddy_fini()` may iterate `free_trees` when it was never allocated. This is CLASS_C crash/DoS behavior. This is not active structured UAF, fixed stale storage UAF, repeated refcount corruption, RCU lifetime mismatch, or controlled kernel memory corruption. The demonstrated consequence is kernel panic on a module load error path. A theoretical stronger consequence is not supported because there is no attacker-controlled payload, no object replacement, no callback dispatch, no arbitrary read/write, and no security-boundary bypass. ImportantCandidate=NO because the evidence supports a host-admin-gated crash-only initialization bug. AutoDowngradeAllowed=YES because no unresolved corruption, ownership, authorization, or lifetime primitive would be lost by treating it as ordinary Moderate/Low-like operational risk. ## 5. One-sentence report phrase A NULL pointer dereference in the amdgpu VRAM manager initialization error path can panic the kernel if cgroup region registration fails before list and gpu buddy initialization, but reliable triggering appears to require host level driver management and no UAF, privilege escalation, or network reachable primitive is established. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: this is a host-admin-gated NULL dereference on a driver load failure path with no established memory corruption, repeated lifetime mutation, authorization bypass, or below-host-admin trigger. ## 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init() Commit: e184e46ca1ba652ab8053a10a51b39aad06d3f5c Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e184e46ca1ba652ab8053a10a51b39aad06d3f5c Commit description: drmm_cgroup_register_region() is called before INIT_LIST_HEAD() and gpu_buddy_init() in amdgpu_vram_mgr_init(). If it fails, the function returns early and bypasses those initializations. Since adev->mman.initialized is set to true before amdgpu_vram_mgr_init() is called, a failure triggers amdgpu_ttm_fini(), which calls amdgpu_vram_mgr_fini(), which then: - Calls list_for_each_entry_safe() on reservations_pending and reserved_pages, whose list_head::next pointers are zero-initialized (NULL). The loop does not recognize them as empty and dereferences NULL. - Calls gpu_buddy_fini(), which iterates free_trees[] unconditionally via for_each_free_tree(). Since mm->free_trees is NULL (never allocated), this dereferences NULL. Both result in a kernel panic on the module load error path. Fix by moving drmm_cgroup_register_region() to after the list and buddy allocator are fully initialized, so the teardown path is safe to run. Reported-by: Sashiko-bot Closes: https://sashiko.dev/#/patchset/20260428073116.15687-1-thomas.hellstrom@linux.intel.com?part=4 Fixes: 2b624a2 ("drm/ttm: Handle cgroup based eviction in TTM") Cc: Friedrich Vock Cc: Maarten Lankhorst Cc: Tejun Heo Cc: Maxime Ripard Cc: Christian König Cc: Alex Deucher Cc: amd-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v6.14+ Assisted-by: GitHub_Copilot:claude-sonnet-4.6 Signed-off-by: Thomas Hellström Reviewed-by: Arunpravin Paneer Selvam Reviewed-By: Maarten Lankhorst Tested-by: Thadeu Lima de Souza Cascardo Link: https://patch.msgid.link/20260725100036.2372-2-thomas.hellstrom@linux.intel.com Acked-by: Christian König Signed-off-by: Maarten Lankhorst Signed-off-by: Greg Kroah-Hartman Changed files: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.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=e184e46ca1ba652ab8053a10a51b39aad06d3f5c ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-89828 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89828 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:H 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).