From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80980][MODERATE REGULAR] net/smc: stop killed, freed and out_of_sync sharing a byte Date: Fri, 11 Sep 2026 19:23:28 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80980 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: 313f79149eb337411c64e2c247234b62ef9a3cb9 List-Id: CVE: CVE-2026-80980 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: net/smc: stop killed, freed and out_of_sync sharing a byte Commit: 313f79149eb337411c64e2c247234b62ef9a3cb9 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=313f79149eb337411c64e2c247234b62ef9a3cb9 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80980 Analysis date: Fri, 11 Sep 2026 19:23:28 -0400 ActionableScore: 3 ActionableScore lower bound: unknown Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: An SMC connection state race can lose updates to killed freed or out_of_sync because adjacent bitfield writes share one byte, allowing a reachable SMC peer and concurrent local connection handling to corrupt connection state and potentially cause denial of service. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80980 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80980 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-2026-80980 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80980 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-362;CWE-667;CWE-662;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.4';DESCR 'SMC connection state flags killed freed and out_of_sync were implemented as adjacent bitfields in one byte, so writes from different contexts could perform read modify write cycles that overwrite neighboring flag updates. smc_cdc_msg_validate can set out_of_sync from the receive tasklet while smc_conn_kill can set killed from process context, without a common lock. This can corrupt connection state and may leave a connection incorrectly marked as not killed not freed or not out_of_sync. For the CVSS the PR:N value is used because a remote SMC peer may influence CDC receive handling without a local account on the target when an SMC service is reachable. The issue is best treated as adjacent or internal network reachable because SMC is normally deployed in SMC-R or SMC-D capable environments rather than the public Internet. Impact is at least connection level denial of service, with a paranoid risk of broader availability impact and limited confidentiality or integrity impact from inconsistent lifecycle state.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3) SKIP CVE-2026-80980 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE UAF LINUS TEST - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES ## 1. ActionableScore * Raw conservative score: 3 * Conservative score: 3 * Raw paranoid score: 3 * Paranoid score: 3 * Final recommended bucket: **Borderline / manual review recommended**:: No floor or cap was applied. ## 2. Signal breakdown Positive signals: * +2 Remote or adjacent network peer influence: `smc_cdc_msg_validate()` is reached from the SMC receive path, and a peer can influence CDC message handling when an SMC connection is reachable. * +1 Availability or connection-state DoS concern: concurrent read-modify-write updates of adjacent bitfield flags can lose state transitions such as `killed`, `freed`, or `out_of_sync`, causing incorrect SMC connection state. Non-awarded signals: * Real UAF not awarded: no freed object or stale post-lifetime dereference is established. * Strong corruption not awarded: the patch shows lost flag updates, not OOB write, arbitrary write, controlled reclaim, type confusion, or refcount takeover. * Concrete repeated release/refcount not awarded: no first lifetime-ending release followed by a second release on the same dangling reference is shown. * Confidentiality and integrity not awarded: inconsistent connection flags do not establish disclosure or unauthorized modification of protected data. * Reliable kernel crash not awarded: the supplied evidence does not show panic, Oops, or host-wide fatal fault. * Race penalty not applied: although this is a race, the evidence does not prove a one-shot or externally uncontrollable timing condition sufficient for a negative point. * Namespace-scoped privilege not awarded: the supplied evidence does not involve a complete namespace-scoped capability chain. ## 3. Reachability analysis The vulnerable state update involves SMC connection processing. One side is the receive tasklet path, where `smc_cdc_msg_validate()` sets `out_of_sync`. Another side is process context, where `smc_conn_kill()` sets `killed` under `lock_sock()`. A remote or adjacent SMC peer can influence the receive path if an SMC endpoint is reachable. However, the complete triggering sequence also depends on concurrent local process-context connection state changes, so the exact attacker-controlled end-to-end trigger is not fully resolved from the supplied patch alone. Host administrator privilege is not positively established, but complete below-host-admin reachability is also not fully proven. Therefore `HostAdminRequired=UNKNOWN`. No namespace-specific capability path is established. No special namespace setup is shown. SMC-R or SMC-D capable deployment is a prerequisite in practice, usually on internal or data-center networks rather than the public Internet. Race repeatability is plausible under connection churn or error handling, but the patch does not demonstrate reliable attacker-controlled exploitation beyond state inconsistency. ## 4. Primitive and severity interpretation The exact primitive is a data race on adjacent C bitfields sharing one byte. Writes to one flag are compiled as read-modify-write operations on the byte containing all three flags. Concurrent stores from different contexts can overwrite neighboring flag updates. This is not an active structured UAF and not fixed stale storage. It is a synchronization and state-consistency bug affecting SMC connection lifecycle flags. The demonstrated consequence is incorrect connection state, potentially causing connection-level denial of service or incorrect cleanup/error handling. The speculative consequence is broader SMC connection misbehavior if lost `killed`, `freed`, or `out_of_sync` updates lead to later incorrect decisions. No memory corruption primitive, protected-resource access, or privilege escalation path is established. PrimitiveClass is `CLASS_C` because the evidence supports invalid-state behavior without an independently useful kernel corruption primitive. ImportantCandidate is `NO` because there is no UAF, no refcount/lifetime mutation, no controlled memory corruption, no boundary bypass, and no demonstrated LPE. Manual review is still recommended because the race is in a network-reachable connection-state path. AutoDowngradeAllowed is `YES` because this is a Class C state-race issue and the supplied evidence does not establish unresolved Important-grade exploitation leverage. Likely operational severity: borderline Moderate. It should be checked for product exposure to SMC, but it does not currently look like an Important-class kernel vulnerability. ## 5. One-sentence report phrase An SMC connection state race can lose updates to killed freed or out_of_sync because adjacent bitfield writes share one byte, allowing a reachable SMC peer and concurrent local connection handling to corrupt connection state and potentially cause denial of service. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: the issue is network-adjacent and affects lifecycle state flags, but no UAF, controlled corruption, crash, information disclosure, or privilege escalation primitive is established. ## 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net/smc: stop killed, freed and out_of_sync sharing a byte Commit: 313f79149eb337411c64e2c247234b62ef9a3cb9 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=313f79149eb337411c64e2c247234b62ef9a3cb9 Commit description: The three connection state flags are single-bit bitfields, so they occupy one byte of struct smc_connection and every store to one is a read-modify-write of the other two: u8 killed : 1; u8 freed : 1; u8 out_of_sync : 1; They are not written under a common lock. smc_cdc_msg_validate() sets out_of_sync from the receive tasklet, while smc_conn_kill() sets killed from process context under lock_sock(), and the receive path does not defer to the backlog when the socket is owned -- smc_cdc_msg_recv() takes only bh_lock_sock(). Give each flag its own byte so a store no longer touches its neighbours. All readers test them as booleans and are unchanged. struct smc_connection grows by two bytes. Fixes: b286a06 ("net/smc: handle incoming CDC validation message") Cc: stable@vger.kernel.org Reviewed-by: Mahanta Jambigi Signed-off-by: Hidayath Khan Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260820074642.966856-2-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: net/smc/smc.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=313f79149eb337411c64e2c247234b62ef9a3cb9 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80980 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80980 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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 6.4 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).