From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74381][MODERATE REGULAR] gpu: host1x: Allow entries in BO caches to be freed [ Upstream Date: Sat, 15 Aug 2026 17:07:59 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74381 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: 2 X-AL-KERNEL-Commit: af755456299d44e4ed6af3b7c70a7f03ea37fdf1 List-Id: CVE: CVE-2026-74381 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: gpu: host1x: Allow entries in BO caches to be freed [ Upstream Commit: af755456299d44e4ed6af3b7c70a7f03ea37fdf1 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=af755456299d44e4ed6af3b7c70a7f03ea37fdf1 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74381 Analysis date: Sat, 15 Aug 2026 17:07:59 -0400 ActionableScore: 3 ActionableScore lower bound: 2 Actionable bucket: Ordinary Moderate / Low-like, borderline only under resource-exhaustion interpretation Manual review required: NO Summary: Host1x BO caching could create a reference cycle where cached DMA mappings kept buffer objects alive indefinitely, allowing a local user with Tegra DRM or Host1x device access to cause resource exhaustion over time. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74381 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74381 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-2026-74381 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW 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-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'Host1x BO caching could create a reference cycle where a cached DMA mapping kept a strong reference to the underlying buffer object. Because cached mappings were removed only from the BO free path, a cached BO could never reach that free path and could remain allocated indefinitely. A local user or process that can exercise the Tegra DRM or Host1x buffer path may cause repeated BO and DMA mapping leaks, leading to resource exhaustion over time. For the CVSS the PR:L is used for the paranoid score because access to DRM or GPU device interfaces may be delegated to non-root local users on some systems. The issue is not network reachable. Impact is denial of service through memory or DMA resource exhaustion, with no supported evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like, borderline only under resource-exhaustion interpretation (with actual score 3) YES READ LOCK INIT LEAK ERRORPATH UAF DMAorINTERRUPT HARDWARE LINUS MEMORY DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=2 ## 1. ActionableScore * Conservative score: 2 * Paranoid score: 3 * Final recommended bucket: **Ordinary Moderate / Low-like, borderline only under resource-exhaustion interpretation**:: ## 2. Signal breakdown Triggered signals: * Local unprivileged trigger: +1 Tegra DRM or Host1x buffer object paths may be reachable by local users with access to GPU DRM device nodes. * Reliable kernel crash / strong DoS: +1 in paranoid score The bug can cause persistent BO and DMA mapping leaks. Repeated use may exhaust memory or DMA-related resources, but this is gradual resource exhaustion rather than an immediate crash primitive. * Availability impact realistic: +1 in paranoid score only Sustained repeated allocation and caching can plausibly degrade or exhaust system or device resources. Negative or non-applied signals: * Rare AND difficult-to-reach subsystem/configuration: -1 This is Tegra Host1x specific and depends on Tegra DRM BO caching paths, not a broad default kernel subsystem. * No generic memory corruption signal The patch fixes a reference cycle and resource leak. It does not show UAF, double free, OOB write, type confusion, arbitrary write, stale callback, or attacker-controlled reclaim. * No privilege escalation signal There is no supported LPE primitive. The bug prevents freeing objects rather than freeing too early or reusing stale memory. * No confidentiality or integrity impact No information disclosure, cross-object overwrite, page-cache corruption, or security-boundary bypass is indicated. ## 3. Reachability analysis A local process that can exercise Tegra DRM or Host1x BO pinning with caching may trigger the leak by repeatedly creating and releasing buffer objects that enter the BO cache. This is not network reachable and not firmware-mediated. Namespace or container relevance depends on whether DRM device nodes are exposed into the container. If `/dev/dri` or related Tegra device nodes are delegated to an untrusted container or user, PR:L is reasonable. If access is restricted to trusted system services, practical exposure is lower. The affected path is hardware and driver specific, so exposure is limited to Tegra systems using this Host1x BO cache functionality. Call-site confidence: high. The patch includes the relevant pin, unpin, cache, and GEM free paths. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource exhaustion issue, not an Important-class vulnerability. The theoretical risk is denial of service through leaked BO and DMA mapping resources after repeated local use. Realistic exploitation evidence points to resource exhaustion only. There is no demonstrated memory corruption, privilege escalation, sensitive data exposure, or cross-boundary ownership violation. ## 5. One-sentence report phrase Host1x BO caching could create a reference cycle where cached DMA mappings kept buffer objects alive indefinitely, allowing a local user with Tegra DRM or Host1x device access to cause resource exhaustion over time. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This is a resource leak without a concrete memory-corruption or security-boundary-bypass primitive. It can be handled as non-urgent unless the affected product exposes Tegra DRM device nodes to untrusted local users and has strict availability requirements. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: gpu: host1x: Allow entries in BO caches to be freed [ Upstream Commit: af755456299d44e4ed6af3b7c70a7f03ea37fdf1 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=af755456299d44e4ed6af3b7c70a7f03ea37fdf1 Changed files: drivers/gpu/drm/tegra/gem.c drivers/gpu/drm/tegra/submit.c drivers/gpu/host1x/bus.c include/linux/host1x.h 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=af755456299d44e4ed6af3b7c70a7f03ea37fdf1 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74381 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74381 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:L/PR:L/UI:N/S:U/C:N/I:N/A:L 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: 2 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).