* [CVE-2026-80863][IMPORTANT] RDMA/rxe: Fix OOB in free_rd_atomic_resources()
@ 2026-09-04 22:10 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-04 22:10 UTC (permalink / raw)
To: kernel-cve
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:
<TASK>
__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
</TASK>
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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