From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80986][MODERATE 7.0] net/smc: bound the peer rkey counts in SMC-Rv2 LLC messages Date: Sat, 12 Sep 2026 04:12:09 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80986 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: 486c699a8cde82c1d9b4f443eeab4ddf86358cb0 List-Id: CVE: CVE-2026-80986 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: net/smc: bound the peer rkey counts in SMC-Rv2 LLC messages Commit: 486c699a8cde82c1d9b4f443eeab4ddf86358cb0 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=486c699a8cde82c1d9b4f443eeab4ddf86358cb0 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80986 Analysis date: Sat, 12 Sep 2026 04:12:09 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80986 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80986 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-80986 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80986 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-125;CWE-126;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.6';DESCR 'An out-of-bounds read in the SMC-Rv2 LLC rkey handling path can occur when the device has max_recv_sge is 1 and no shared v2 receive buffer is used. In this case only the inline LLC message is copied into the queue entry, but smc_llc_save_add_link_rkeys can still parse the v2 extension past the copied buffer and smc_llc_rmt_delete_rkey can also iterate rkey entries beyond the buffer it points to. A remote SMC/RDMA peer that can establish or influence an SMC-Rv2 link can trigger the vulnerable parsing path during link addition or rkey deletion, causing a kernel slab out-of-bounds read and likely denial of service through KASAN report or kernel crash. For the CVSS the PR:N is used because the attacker does not need a local account on the victim and only needs network adjacency to the exposed SMC/RDMA fabric. The issue is rated AV:A rather than AV:N because SMC-Rv2 over RDMA is normally limited to local storage or data center networks. Impact is at least denial of service. For paranoid triage, limited confidentiality or integrity impact is kept because kernel heap data is read out of bounds and may influence rkey state, but there is no clear arbitrary write or direct information disclosure primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate (with actual score 5) YES READ KASAN OOB KERNEL_PANIC_PLUS_UAF HARDWARE LINUS KPANIC DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 PrimitiveClass=CLASS_B RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=NO 1. ActionableScore * Raw conservative score: 4 * Conservative score: 4. No floor or cap applied. * Raw paranoid score: 5 * Paranoid score: 5. No floor or cap applied. * Final recommended bucket: **Actionable Moderate**:: 2. Signal breakdown Conservative signals: * +2: Network-adjacent reachable SMC/RDMA peer can reach the vulnerable SMC-Rv2 LLC rkey parsing path during link addition or rkey deletion. * +1: Kernel slab out-of-bounds read is directly established by the patch and KASAN report. * +1: Reliable DoS is supported because the invalid kernel heap read can trigger KASAN report, Oops, or kernel crash. * 0: No host-admin penalty. The attacker model is a peer on the SMC/RDMA fabric, not a local host administrator. * 0: No rare-hardware penalty. The max_recv_sge == 1 condition is specific, but the evidence does not prove a rare or physical-only deployment requirement. Paranoid additional signal: * +1: The out-of-bounds data can influence rkey loop bounds and values consumed by smc_rtoken_set() or smc_rtoken_delete(), so limited active rkey state corruption remains unresolved beyond a pure immediate fault. Important non-awarded signals: * Controlled reclaim not demonstrated. * Arbitrary write not demonstrated. * User-visible information disclosure not demonstrated. * Real UAF not established. * Concrete repeated release/refcount mutation not established. * Confidentiality is not awarded because the kernel heap bytes read out of bounds are not shown to be returned to the peer or userspace. * Strong integrity impact is not awarded because rkey state influence is indirect and not shown to provide attacker-directed corruption. * Extra availability point is not awarded because the same crash is already counted once. * Strong LPE or strong exploitation leverage is not awarded because there is no controlled object replacement, callback control, arbitrary R/W, or demonstrated privilege escalation. 3. Reachability analysis The plausible attacker is a remote SMC/RDMA peer with access to the same SMC-Rv2 capable RDMA fabric. The issue is not public Internet generic TCP reachability, but it is reachable across a storage or data-center adjacent network where SMC-Rv2 is exposed. Host administrator privileges on the victim are not required for the peer-side trigger once the vulnerable SMC/RDMA service and topology exist. Namespace-scoped privilege is not relevant to this trigger. The complete trigger depends on an SMC-Rv2 link using a device path with max_recv_sge == 1 and no shared v2 receive buffer. That is a deployment prerequisite, but the supplied evidence does not prove it is rare enough to justify a scoring penalty. No timing race is required. The commit states the add-link case happens on every SMC-Rv2 link addition in the affected configuration, regardless of what the peer sends. The peer-declared rkey count can make later reads go further in the affected paths. 4. Primitive and severity interpretation The exact primitive is a slab out-of-bounds read from an SMC LLC queue entry because the code parses a v2 extension or rkey array beyond the buffer that was actually copied. This is not a UAF and not a repeated refcount/lifetime mutation. The primitive is stronger than a purely local assertion because it is reachable from an adjacent network peer and because the out-of-bounds values can be consumed by active SMC rkey management logic. However, the established evidence still mainly supports DoS. The useful non-crash exploitation leverage is unresolved and limited. PrimitiveClass is CLASS_B in the paranoid interpretation because active rkey state may be affected by values read beyond the intended message buffer. It is not CLASS_A because there is no attacker-controlled overwrite, controlled reclaim, arbitrary read/write, callback hijack, or demonstrated LPE. ImportantCandidate is NO because the evidence does not establish a strong Important-preserving primitive. AutoDowngradeAllowed is NO because a network-adjacent kernel heap OOB read with possible active rkey state effects should not be automatically closed without human review, even though the likely operational severity is Actionable Moderate rather than Important. 5. One-sentence report phrase An SMC-Rv2 peer can trigger a kernel slab out-of-bounds read in LLC rkey handling on links without a shared v2 receive buffer, leading primarily to denial of service and requiring manual review because parsed out-of-bounds values may influence rkey state. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: this is network-adjacent kernel heap OOB read in SMC/RDMA control message handling, with DoS clearly supported and limited unresolved rkey-state impact, but without evidence of arbitrary write, disclosure, UAF, or LPE. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net/smc: bound the peer rkey counts in SMC-Rv2 LLC messages Commit: 486c699a8cde82c1d9b4f443eeab4ddf86358cb0 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=486c699a8cde82c1d9b4f443eeab4ddf86358cb0 Commit description: On a link whose device has max_recv_sge == 1 there is no shared v2 receive buffer, and smc_llc_save_add_link_rkeys() takes the v2 extension from 44 bytes past the start of the queue entry's inline message: ext = (struct smc_llc_msg_add_link_v2_ext *)(llc_msg + SMC_WR_TX_SIZE); The entry is a 72-byte allocation and the extension starts at offset 68, so ext->num_rkeys at offset 94 is already past it. This happens on every SMC-Rv2 link addition, whatever the peer sends: [ 2.490065] BUG: KASAN: slab-out-of-bounds in smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.490431] Read of size 2 at addr ffff8880056406de by task smctest/106 [ 2.490709] [ 2.490792] CPU: 0 UID: 0 PID: 106 Comm: smctest Not tainted 7.2.0-rc5-p1-g77a5d9d9c99f #32 PREEMPT(lazy) [ 2.490795] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 2.490798] Call Trace: [ 2.490803] [ 2.490805] dump_stack_lvl+0x53/0x70 [ 2.490810] print_report+0xd0/0x630 [ 2.490828] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 2.490832] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.490834] kasan_report+0xce/0x100 [ 2.490836] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.490837] smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.490839] ? smcr_buf_map_lgr+0x1bf/0x2b0 [ 2.490844] smc_llc_cli_add_link+0xca7/0x1e80 [ 2.490848] ? smc_llc_wait+0x355/0x810 [ 2.490850] ? __pfx_smc_llc_wait+0x10/0x10 [ 2.490851] ? __pfx_smc_llc_cli_add_link+0x10/0x10 [ 2.490853] ? __pfx_autoremove_wake_function+0x10/0x10 [ 2.490863] __smc_connect+0x3f5c/0x4980 [ 2.490873] ? __pfx_kernel_connect+0x10/0x10 [ 2.490888] ? __pfx___smc_connect+0x10/0x10 [ 2.490891] ? release_sock+0x148/0x1d0 [ 2.490894] smc_connect+0x42c/0x580 [ 2.490896] __sys_connect+0xfc/0x130 [ 2.490898] ? __pfx___sys_connect+0x10/0x10 [ 2.490900] ? handle_mm_fault+0x1a1/0x430 [ 2.490908] __x64_sys_connect+0x6d/0xb0 [ 2.490909] ? fpregs_assert_state_consistent+0x56/0xe0 [ 2.490917] do_syscall_64+0xf9/0x540 [ 2.490921] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 2.490924] RIP: 0033:0x421bb4 [ 2.490927] Code: ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 80 3d ad 34 09 00 00 74 13 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4c c3 0f 1f 00 55 48 89 e5 48 83 ec 10 89 55 [ 2.490929] RSP: 002b:00007ffd473b01a8 EFLAGS: 00000202 ORIG_RAX: 000000000000002a [ 2.490935] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000421bb4 [ 2.490936] RDX: 0000000000000010 RSI: 00007ffd473b01d0 RDI: 0000000000000003 [ 2.490937] RBP: 0000000000003930 R08: 0000000000000004 R09: 0000000000000000 [ 2.490938] R10: 00007ffd473b0f98 R11: 0000000000000202 R12: 0000000000000006 [ 2.490939] R13: 00007ffd473b0f87 R14: 0000000000000003 R15: 00007ffd473b0f90 [ 2.490940] [ 2.490941] [ 2.499545] Allocated by task 44: [ 2.499693] kasan_save_stack+0x33/0x60 [ 2.499860] kasan_save_track+0x14/0x30 [ 2.500026] __kasan_kmalloc+0x8f/0xa0 [ 2.500190] __kmalloc_cache_noprof+0x158/0x370 [ 2.500393] smc_llc_enqueue+0x72/0x560 [ 2.500559] smc_wr_rx_tasklet_fn+0x474/0xa80 [ 2.500747] tasklet_action_common+0x20f/0x8a0 [ 2.500945] handle_softirqs+0x18e/0x590 [ 2.501115] do_softirq+0x3b/0x60 [ 2.501266] __local_bh_enable_ip+0x61/0x70 [ 2.501446] __alloc_skb+0x732/0x890 [ 2.501604] rxe_init_packet+0x16b/0x4f0 [ 2.501783] prepare_ack_packet+0xb8/0x830 [ 2.501962] rxe_receiver+0x495/0x96e0 [ 2.502125] do_work+0x144/0x470 [ 2.502269] process_one_work+0x633/0x1030 [ 2.502450] worker_thread+0x45b/0xd10 [ 2.502617] kthread+0x2c6/0x3b0 [ 2.502762] ret_from_fork+0x36e/0x5a0 [ 2.502925] ret_from_fork_asm+0x1a/0x30 [ 2.503103] [ 2.503177] The buggy address belongs to the object at ffff888005640680 [ 2.503177] which belongs to the cache kmalloc-96 of size 96 [ 2.503692] The buggy address is located 22 bytes to the right of [ 2.503692] allocated 72-byte region [ffff888005640680, ffff8880056406c8) [ 2.504227] [ 2.504300] The buggy address belongs to the physical page: [Commit description truncated; see the upstream URL below] Changed files: net/smc/smc_llc.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=486c699a8cde82c1d9b4f443eeab4ddf86358cb0 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80986 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80986 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 7.6 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).