From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72102][MODERATE 7.0] dm_early_create: fix freeing used table on dm_resume failure Date: Sun, 16 Aug 2026 09:07:37 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72102 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 3ba377a47a093cc19647ca7f102acd33a211d472 List-Id: CVE: CVE-2026-72102 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: dm_early_create: fix freeing used table on dm_resume failure Commit: 3ba377a47a093cc19647ca7f102acd33a211d472 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ba377a47a093cc19647ca7f102acd33a211d472 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72102 Analysis date: Sun, 16 Aug 2026 09:07:37 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: A device mapper early boot error path could destroy a table after it had already been installed with `dm_swap_table()`, creating a double-free or use-after-free candidate that can cause boot-time denial of service and warrants manual review despite requiring privileged boot configuration control. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72102 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72102 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 7.0 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-2026-72102 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:H/UI:N/S:U/C:L/I:L/A:H';CWE-415;*CWE-416;CWE-703;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.6';DESCR 'A device mapper early boot error path can call dm_table_destroy() after dm_swap_table() has already installed the table into the mapped device. If dm_resume() then fails, the old cleanup path may free a table that is already owned by the device mapper core, creating a double free or use after free candidate during subsequent cleanup. For the CVSS the PR:H is used because reliable triggering normally requires control over early boot device mapper configuration or equivalent administrative control. The issue is not network reachable and is limited to local or boot time configuration paths. Impact is at least denial of service during boot or early device initialization. For the paranoid score, limited confidentiality and integrity impact is kept because the bug class is memory corruption, but practical privilege escalation is not strongly supported by the trigger context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES DISK SIMPLEFIX HARDWARE LINUS KPANIC INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum**:: ## 2. Signal breakdown Triggered signals: * Generic memory corruption: +2 The commit explicitly describes freeing a table with `dm_table_destroy()` after it was already installed via `dm_swap_table()`. This is a double-free or use-after-free candidate. * Real lifetime corruption: +1 The bug is an ownership/lifetime error. The table ownership has moved to the device mapper core, but the error path still tries to destroy it directly. * Reliable kernel crash / strong DoS: +1 A failed `dm_resume()` during early mapped-device setup can lead to invalid cleanup and likely boot-time crash or device initialization failure. * Important filesystem/storage path: +1 Device mapper is a core block/storage subsystem, and this affects early boot mapping. * Requires admin/root/boot configuration in typical deployments: -2 Reliable triggering normally requires control over early boot device mapper configuration or equivalent administrative control. Paranoid-only signal: * Weak LPE concern / limited C/I concern: +1 Because the primitive is a double-free/UAF candidate in kernel storage code, limited confidentiality or integrity impact is not impossible in worst-case analysis. However, practical privilege escalation is not strongly supported because the trigger is early boot and privileged. ## 3. Reachability analysis The bug is reachable through `dm_early_create()`, an early boot path for directly booting to a mapped device. In normal deployments, an attacker would need control over kernel boot parameters, initramfs configuration, device mapper early setup, or equivalent administrative privileges. This is not network reachable. Namespaces or containers do not normally reduce the privilege requirement because this path is not a regular runtime namespace interface. The affected path is uncommon compared with normal device mapper runtime ioctls, but device mapper itself is a core storage subsystem. Call-site confidence: medium. The provided patch shows the failing error path and the relevant ownership transition via `dm_swap_table()`, but not the full surrounding labels and cleanup code. ## 4. Severity interpretation This behaves more like an actionable Moderate than an ordinary Moderate because the patch fixes a real kernel object lifetime bug, not just validation or bookkeeping. The realistic impact is boot-time or early initialization DoS under privileged configuration control. The theoretical memory corruption potential is stronger than a pure crash because the same table may be freed after ownership was transferred. However, realistic exploitation evidence for privilege escalation is weak due to the early boot context and high privilege requirement. ## 5. One-sentence report phrase A device mapper early boot error path could destroy a table after it had already been installed with `dm_swap_table()`, creating a double-free or use-after-free candidate that can cause boot-time denial of service and warrants manual review despite requiring privileged boot configuration control. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a concrete lifetime/ownership bug with double-free or UAF potential in a core storage subsystem. The practical attack surface is narrow and privileged, but the bug class should not be auto-closed without confirming the exact cleanup sequence and downstream object lifetime behavior. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: dm_early_create: fix freeing used table on dm_resume failure Commit: 3ba377a47a093cc19647ca7f102acd33a211d472 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ba377a47a093cc19647ca7f102acd33a211d472 Commit description: If dm_resume fails, the kernel attempts to free table with dm_table_destroy, but the table was already instantiated with dm_swap_table. This commit skips the call to dm_table_destroy in this case. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-4.6 Fixes: 6bbc923 ("dm: add support to directly boot to a mapped device") Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Changed files: drivers/md/dm-ioctl.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=3ba377a47a093cc19647ca7f102acd33a211d472 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72102 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72102 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:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.6 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: 4 Paranoid ActionableScore: 5 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: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).