From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80863][IMPORTANT] RDMA/rxe: Fix OOB in free_rd_atomic_resources() Date: Fri, 04 Sep 2026 18:10:11 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80863 X-AL-KERNEL-Priority: IMPORTANT X-AL-KERNEL-Severity: IMPORTANT X-AL-KERNEL-Base-Severity: IMPORTANT X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 7 X-AL-KERNEL-ActionableScore-Lower: 5 X-AL-KERNEL-Commit: 142c8165b7974b40fa62c393653edb5c00b8b5fe List-Id: CVE: CVE-2026-80863 Priority: IMPORTANT AL-KERNEL base severity: IMPORTANT KPANIC flag: YES Patch: RDMA/rxe: Fix OOB in free_rd_atomic_resources() Commit: 142c8165b7974b40fa62c393653edb5c00b8b5fe Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=142c8165b7974b40fa62c393653edb5c00b8b5fe Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80863 Analysis date: Fri, 04 Sep 2026 18:10:11 -0400 ActionableScore: 7 ActionableScore lower bound: 5 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80863 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80863 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: IMPORTANT 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-2026-80863 IMPORTANT https://www.kernelcve.org/list/?q=CVE-2026-80863 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-122;CWE-119;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'An OOB write in RDMA/RXE free_rd_atomic_resources can occur because qp attr max_dest_rd_atomic is updated before the old rd atomic resources array is freed. The free path then uses the new larger bound while walking the old smaller allocation, which can write past the kmalloc object and corrupt slab memory. For the CVSS the PR:L because a local user or process with access to RDMA uverbs and an RXE device can reach rxe_modify_qp through ib_uverbs_write without needing full root on the host. The issue is not directly network reachable because the triggering operation is a local uverbs control path rather than inbound RDMA traffic. Impact is at least local denial of service via KASAN report or kernel crash, and the OOB write makes limited or full confidentiality and integrity impact plausible enough for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) YES WRITE OOB DANGER UAF NETWORK KERNEL_PANIC_PLUS_UAF HARDWARE LINUS KPANIC NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=7 ActionableScoreLower=5 1. ActionableScore * Conservative score: 5 * Paranoid score: 7 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: 2. Signal breakdown * Local unprivileged trigger: +1. The call path goes through ib_uverbs_write -> ib_uverbs_modify_qp -> rxe_modify_qp, so a local process with access to RDMA uverbs and an RXE device can plausibly trigger it without full host root. * Memory corruption, strong corruption primitive: +2. KASAN reports a slab out-of-bounds write in free_rd_atomic_resource/free_rd_atomic_resources. * Reliable kernel crash / strong DoS: +1. The provided trace demonstrates a KASAN-detected kernel memory error reachable from the modify_qp path. * Weak LPE concern conservative: +1. The bug is a slab OOB write, but the write appears tied to cleanup/bookkeeping rather than an obvious attacker-chosen arbitrary write primitive. * Privilege escalation plausible paranoid: +2. For the paranoid score, slab OOB write from a local kernel interface is enough to justify manual-review sensitivity for possible LPE, even though exploit reliability is not demonstrated. * Integrity impact plausible: +1. A kernel slab OOB write can corrupt adjacent kernel metadata or objects. * Confidentiality impact plausible paranoid: +1. Not demonstrated directly, but included in the paranoid score due to possible secondary effects of slab corruption. * Rare or configuration-dependent subsystem: -1. RXE/RDMA uverbs exposure depends on RDMA stack availability, device setup, and device-node permissions. * Constrained or low-control overwrite uncertainty: -1 conservative. The visible primitive is a size 4 OOB write in a resource-freeing path, with no demonstrated arbitrary target or payload control. 3. Reachability analysis The bug is locally reachable through the RDMA uverbs control path when RXE is configured and the attacker can access the relevant uverbs device. It is not directly network-triggerable because the trigger is modify_qp through a local file descriptor, not inbound RDMA packet processing. Namespace or container setups may matter if RDMA devices are delegated into containers or if uverbs device permissions are relaxed. Call-site confidence: high, because the supplied trace shows the concrete path from ib_uverbs_write to rxe_qp_from_attr and the patch changes the exact ordering that controls the free loop bound. 4. Severity interpretation This is stronger than an ordinary Moderate because the demonstrated failure is a real slab out-of-bounds write, not only a warning, leak, or validation cleanup. The realistic impact is local DoS and kernel crash from a user-reachable device API. The theoretical risk includes privilege escalation because local slab OOB writes have historically been exploitable, but this specific patch does not show arbitrary write, controlled reclaim, callback control, or a proven exploit chain. Therefore the conservative score is Actionable Moderate, while the paranoid score is a Strong Important candidate requiring manual review. 5. One-sentence report phrase A local slab out-of-bounds write in RDMA/RXE free_rd_atomic_resources can be triggered through the uverbs modify_qp path when max_dest_rd_atomic is updated before freeing the old rd_atomic array, causing kernel memory corruption and at least a reliable DoS with possible LPE risk. 6. Manual review recommendation MANUAL CHECK REQUIRED. This is a local kernel slab OOB write with a concrete KASAN trace and a plausible privilege-escalation concern, even though the exact exploitability beyond DoS is not demonstrated. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: RDMA/rxe: Fix OOB in free_rd_atomic_resources() Commit: 142c8165b7974b40fa62c393653edb5c00b8b5fe Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=142c8165b7974b40fa62c393653edb5c00b8b5fe Commit description: free_rd_atomic_resources() iterates using qp->attr.max_dest_rd_atomic. Updating max_dest_rd_atomic before freeing the old array can make the free path walk past the old allocation and trigger a slab out-of-bounds write catched by KASAN: ================================================================== BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resource drivers/infiniband/sw/rxe/rxe_qp.c:180 [inline] BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:171 [inline] BUG: KASAN: slab-out-of-bounds in free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:163 [inline] BUG: KASAN: slab-out-of-bounds in rxe_qp_from_attr+0x1e88/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:712 Write of size 4 at addr ffff88802b8dddb8 by task syz.3.451/11063 CPU: 0 UID: 0 PID: 11063 Comm: syz.3.451 Not tainted 7.1.0 #2 PREEMPT(full) 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 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x10e/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xf7/0x600 mm/kasan/report.c:482 kasan_report+0xe4/0x120 mm/kasan/report.c:595 free_rd_atomic_resource drivers/infiniband/sw/rxe/rxe_qp.c:180 [inline] free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:171 [inline] free_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:163 [inline] rxe_qp_from_attr+0x1e88/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:712 rxe_modify_qp+0x1e2/0x530 drivers/infiniband/sw/rxe/rxe_verbs.c:623 ib_security_modify_qp+0x223/0xfa0 drivers/infiniband/core/security.c:625 _ib_modify_qp+0x333/0xec0 drivers/infiniband/core/verbs.c:1915 modify_qp+0x13ca/0x1940 drivers/infiniband/core/uverbs_cmd.c:1932 ib_uverbs_modify_qp+0xcb/0x120 drivers/infiniband/core/uverbs_cmd.c:1958 ib_uverbs_write+0xb86/0x1030 drivers/infiniband/core/uverbs_main.c:680 vfs_write+0x2aa/0x1070 fs/read_write.c:686 ksys_write+0x1f8/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fefc75a70cd Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fefc8495018 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fefc7835fa0 RCX: 00007fefc75a70cd RDX: 0000000000000078 RSI: 0000200000000240 RDI: 0000000000000007 RBP: 00007fefc764f10f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fefc7836038 R14: 00007fefc7835fa0 R15: 00007ffcf0586aa0 Allocated by task 11063: kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5296 [inline] __kmalloc_noprof+0x32a/0x850 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] alloc_rd_atomic_resources drivers/infiniband/sw/rxe/rxe_qp.c:155 [inline] rxe_qp_from_attr+0x3f8/0x2150 drivers/infiniband/sw/rxe/rxe_qp.c:714 rxe_modify_qp+0x1e2/0x530 drivers/infiniband/sw/rxe/rxe_verbs.c:623 ib_security_modify_qp+0x223/0xfa0 drivers/infiniband/core/security.c:625 _ib_modify_qp+0x333/0xec0 drivers/infiniband/core/verbs.c:1915 modify_qp+0x13ca/0x1940 drivers/infiniband/core/uverbs_cmd.c:1932 ib_uverbs_modify_qp+0xcb/0x120 drivers/infiniband/core/uverbs_cmd.c:1958 ib_uverbs_write+0xb86/0x1030 drivers/infiniband/core/uverbs_main.c:680 vfs_write+0x2aa/0x1070 fs/read_write.c:686 ksys_write+0x1f8/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802b8ddd80 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes to the right of allocated 56-byte region [ffff88802b8ddd80, ffff88802b8dddb8) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b8dd flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff888015c418c0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000 [Commit description truncated; see the upstream URL below] Changed files: drivers/infiniband/sw/rxe/rxe_qp.c lib/dump_stack.c mm/kasan/report.c drivers/infiniband/sw/rxe/rxe_verbs.c drivers/infiniband/core/security.c drivers/infiniband/core/verbs.c drivers/infiniband/core/uverbs_cmd.c drivers/infiniband/core/uverbs_main.c fs/read_write.c arch/x86/entry/syscall_64.c mm/kasan/common.c include/linux/kasan.h mm/slub.c include/linux/slab.h include/linux/page_owner.h mm/page_alloc.c security/tomoyo/realpath.c security/tomoyo/file.c security/tomoyo/tomoyo.c security/security.c fs/open.c fs/namei.c security/selinux/hooks.c fs/dcache.c fs/kernfs/dir.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=142c8165b7974b40fa62c393653edb5c00b8b5fe ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80863 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80863 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:L/I:L/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7.8 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: 5 Paranoid ActionableScore: 7 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: IMPORTANT KPANIC detected for this report: YES Published priority for this report (same as in Subject): IMPORTANT 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).