From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68240][LOW] drm/gpusvm: publish dpagemap early to avoid device mapping leak on error Date: Mon, 10 Aug 2026 16:38:08 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68240 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: 2 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: e8362523fd1b61712f7d996802f9b5dee545c7e6 List-Id: CVE: CVE-2026-68240 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: drm/gpusvm: publish dpagemap early to avoid device mapping leak on error Commit: e8362523fd1b61712f7d996802f9b5dee545c7e6 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e8362523fd1b61712f7d996802f9b5dee545c7e6 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68240 Analysis date: Mon, 10 Aug 2026 16:38:08 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A local DRM/GPU SVM error path can leak device mappings when drm_gpusvm_get_pages() fails after partial mapping, potentially allowing resource exhaustion but not showing a concrete confidentiality, integrity, or privilege escalation primitive. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68240 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68240 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-2026-68240 LOW 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:L/UI:N/S:U/C:N/I:N/A:H';*CWE-772;*CWE-401;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A device mapping leak in DRM/GPU SVM can occur when drm_gpusvm_get_pages maps one or more device pages and then fails on a later page before svm_pages dpagemap is published. This makes the error cleanup path skip device_unmap for mappings already created, so repeated failures may accumulate leaked GPU or IOMMU device mappings and cause resource exhaustion. For the CVSS the PR:L is used because a local process with access to the DRM/GPU SVM interface can plausibly trigger the error path, while no network or unauthenticated remote path is indicated. The issue is not directly network reachable and requires local interaction with the GPU memory management interface. Impact is denial of service through resource exhaustion. No direct confidentiality or integrity primitive is visible from the code change context because the bug is a cleanup resource leak rather than a proven stale mapping use primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) SKIP CVE-2026-68240 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: f70da6f99d4f40c5f481c92e3b65d5e36eaa6dc9 YES NO NO unknown MAYBE SIMPLEFIX LEAK HARDWARE - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Triggered signals: * Local unprivileged trigger: +1 A local process with access to the DRM/GPU SVM interface may be able to trigger the error path. This is plausible through normal GPU device access rather than requiring full host root. * Availability impact realistic: +1 in paranoid scoring only Repeated failures may accumulate leaked device mappings and potentially exhaust GPU/IOMMU or related mapping resources. This is resource exhaustion, not memory corruption. Subtracting signals: * Hard or special triggering conditions: -1 in conservative scoring The bug requires partial success followed by a later failure in drm_gpusvm_get_pages(), for example mixed page handling with ctx->allow_mixed false. A single ordinary call is not clearly enough to cause system-wide failure. Not awarded: * No remote/network reachability. * No strong memory corruption primitive. * No UAF, double free, OOB write, arbitrary write, callback corruption, or type confusion shown. * No privilege escalation plausibility beyond generic resource exhaustion. * No confidentiality or integrity impact supported by the patch. ## 3. Reachability analysis The likely trigger is a local process interacting with DRM/GPU SVM memory management. On systems where GPU render nodes or relevant DRM interfaces are available to unprivileged users, PR is effectively local low privilege. Namespaces do not obviously create a separate remote or container escape path, but containerized workloads with GPU device access could potentially trigger the same local device path. The issue is not default reachable over the network. It also depends on a GPU/SVM configuration and on reaching an error path after at least one device page has already been mapped. This makes practical exploitation more like repeated local resource leakage than an immediate crash or corruption primitive. Call-site confidence: medium. The provided diff shows the mapping and cleanup relation directly, but not all callers or deployment-specific GPU access controls. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource leak. The patch fixes an error-path cleanup problem where device mappings created by device_map() were not later released by device_unmap() because svm_pages->dpagemap was still NULL. The theoretical worst case is sustained local resource exhaustion if the failing path can be repeated. The realistic evidence does not show memory corruption, stale mapping use as an access primitive, unauthorized memory access, privilege escalation, or cross-security-boundary data modification. Therefore it should not be treated as an Important-class candidate based on the supplied patch. ## 5. One-sentence report phrase A local DRM/GPU SVM error path can leak device mappings when drm_gpusvm_get_pages() fails after partial mapping, potentially allowing resource exhaustion but not showing a concrete confidentiality, integrity, or privilege escalation primitive. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This can likely be auto-closed or handled as low-priority Moderate unless product-specific evidence shows unprivileged users can reliably exhaust GPU/IOMMU mappings quickly or that leaked mappings remain usable as a stale access primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/gpusvm: publish dpagemap early to avoid device mapping leak on error Commit: e8362523fd1b61712f7d996802f9b5dee545c7e6 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e8362523fd1b61712f7d996802f9b5dee545c7e6 Commit description: drm_gpusvm_get_pages() only stored the local dpagemap into svm_pages->dpagemap on the success path. If a later page failed (e.g. -EOPNOTSUPP when ctx->allow_mixed is false) and jumped to err_unmap, svm_pages->dpagemap was still NULL, so __drm_gpusvm_unmap_pages() skipped device_unmap() and leaked the device mappings already created. Assign svm_pages->dpagemap when the first device page is mapped so the err_unmap path can device_unmap() those mappings. This issue was found by Sashiko AI review. Fixes: f70da6f ("drm/gpusvm: pull out drm_gpusvm_pages substructure") Cc: stable@vger.kernel.org Reviewed-by: Matthew Brost Signed-off-by: Honglei Huang Signed-off-by: Matthew Brost Link: https://patch.msgid.link/20260701062800.409248-4-honghuan@amd.com [ Adjusted for 6.18.y: drop drm_pagemap_get()/drm_pagemap_put() around the svm_pages->dpagemap assignment; that reference counting is not present in 6.18 where the field is not refcounted (unmap path only clears it). ] Signed-off-by: Honglei Huang Signed-off-by: Sasha Levin Changed files: drivers/gpu/drm/drm_gpusvm.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=e8362523fd1b61712f7d996802f9b5dee545c7e6 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68240 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68240 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:L 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: 1 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: 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).