EUVD-2026-59531
GHSA-hggw-gjv7-4223
Severity by source
Sources disagree (Medium–Critical)AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Triggered locally by kernel NVMe scanning only on sparse-NUMA hardware (AV:L, AC:H) and requires privileged control over hardware/kernel config (PR:H); impact is kernel memory corruption/crash, so A:H, I:L, C:N.
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CVSS VectorVendor: Linux
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
nvme-multipath: fix flex array size in struct nvme_ns_head
struct nvme_ns_head contains a flexible array member, current_path[], which is indexed using the NUMA node ID: head->current_path[numa_node_id()]
The structure is currently allocated as: size = sizeof(struct nvme_ns_head) + (num_possible_nodes() * sizeof(struct nvme_ns *)); head = kzalloc(size, GFP_KERNEL);
This allocation assumes that NUMA node IDs are sequential and densely packed from 0 .. num_possible_nodes() - 1. While this assumption holds on many systems, it is not always true on some architectures such as powerpc.
On some powerpc systems, NUMA node IDs can be sparse. For example: NUMA: NUMA node(s): 6 NUMA node0 CPU(s): 80-159 NUMA node8 CPU(s): 0-79 NUMA node252 CPU(s): NUMA node253 CPU(s): NUMA node254 CPU(s): NUMA node255 CPU(s):
That is, the possible/online NUMA node IDs are: 0, 8, 252, 253, 254, 255 In this case: num_possible_nodes() = 6
So memory is allocated for only 6 entries in current_path[]. However, the array is later indexed using the actual NUMA node ID. As a result, accesses such as: head->current_path[8] or head->current_path[252] goes out of bounds, leading to the following KASAN splat:
============== BUG: KASAN: slab-out-of-bounds in nvme_mpath_revalidate_paths+0x22c/0x290 [nvme_core] Write of size 8 at addr c00020003bda35b8 by task kworker/u641:2/1997
CPU: 1 UID: 0 PID: 1997 Comm: kworker/u641:2 Not tainted 7.1.0-rc5-dirty #14 PREEMPT(lazy) Hardware name: 8335-GTH POWER9 0x4e1202 opal:skiboot-v6.5.3-35-g1851b2a06 PowerNV Workqueue: async async_run_entry_fn Call Trace: [c000200037fa7510] [c0000000021c23d4] dump_stack_lvl+0x88/0xdc (unreliable) [c000200037fa7540] [c0000000009fda90] print_report+0x22c/0x67c [c000200037fa7630] [c0000000009fd508] kasan_report+0x108/0x220 [c000200037fa7740] [c0000000009fff48] __asan_store8+0xe8/0x120 [c000200037fa7760] [c008000018e76474] nvme_mpath_revalidate_paths+0x22c/0x290 [nvme_core] [c000200037fa7800] [c008000018e6556c] nvme_update_ns_info+0x4a4/0x5e0 [nvme_core] [c000200037fa7a50] [c008000018e66270] nvme_alloc_ns+0x6d8/0x1a70 [nvme_core] [c000200037fa7c20] [c008000018e679fc] nvme_scan_ns+0x3f4/0x630 [nvme_core] [c000200037fa7d10] [c00000000031f22c] async_run_entry_fn+0x9c/0x3a0 [c000200037fa7db0] [c0000000002fa544] process_one_work+0x414/0xa10 [c000200037fa7ec0] [c0000000002fbf00] worker_thread+0x320/0x640 [c000200037fa7f80] [c00000000030d0f8] kthread+0x278/0x290 [c000200037fa7fe0] [c00000000000ded8] start_kernel_thread+0x14/0x18
Allocated by task 1997 on cpu 1 at 35.928317s:
The buggy address belongs to the object at c00020003bda3000 which belongs to the cache kmalloc-rnd-15-2k of size 2048 The buggy address is located 16 bytes to the right of allocated 1448-byte region [c00020003bda3000, c00020003bda35a8)
The buggy address belongs to the physical page:
Memory state around the buggy address: c00020003bda3480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 c00020003bda3500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >c00020003bda3580: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc ^ c00020003bda3600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc c00020003bda3680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==============
Fix this by allocating the flexible array using nr_node_ids instead of num_possible_nodes(). Since nr_node_ids represents the maximum possible NUMA node IDs, indexing current_path[] using numa_node_id() becomes safe even on systems with sparse node IDs.
AnalysisAI
Out-of-bounds slab write in the Linux kernel's NVMe-multipath driver (nvme_mpath_revalidate_paths) affects hosts whose NUMA node IDs are sparse rather than densely packed from zero, notably some powerpc/POWER9 systems. The nvme_ns_head.current_path[] flexible array is sized with num_possible_nodes() but indexed with the raw numa_node_id(), so on non-contiguous topologies the driver writes a pointer past the end of the allocation during namespace scanning, producing the KASAN slab-out-of-bounds splat shown in the report. …
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Vulnerability AssessmentAI
| Exploitation | Requires a system whose NUMA node IDs are non-contiguous/sparse (numa_node_id() can exceed num_possible_nodes()-1), as seen on some powerpc/POWER9 machines with node IDs like 0, 8, 252, 253, 254, 255; the kernel must be built with NVMe multipath and must scan/revalidate an NVMe namespace, which invokes nvme_mpath_revalidate_paths and indexes current_path[]. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals conflict sharply and the raw score is misleading. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | On a POWER9 host whose firmware reports sparse NUMA node IDs (e.g. 0, 8, 252-255), the kernel attaches an NVMe namespace and calls nvme_mpath_revalidate_paths, which writes head->current_path[numa_node_id()] using a node ID far larger than the six allocated slots, corrupting the adjacent slab object and tripping KASAN. … |
| Remediation | Vendor-released patch: update to a fixed stable kernel - 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, or 7.1.5 (mainline 7.2-rc1) - whichever matches your branch; the fix simply sizes current_path[] with nr_node_ids instead of num_possible_nodes(). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify Linux systems with sparse NUMA configurations (particularly POWER9 architecture) using NVMe multipath storage by checking /sys/devices/system/node/ for non-contiguous node IDs. …
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Same technique Buffer Overflow
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