CVE-2026-74384

nvme-multipath: fix flex array size in struct nvme_ns_head

Published Aug 15, 2026 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8781-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-8816-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8816-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8816-3 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-8816-4 Linux kernel (GKE) vulnerabilities
Ubuntu USN Ubuntu USN USN-8876-1 Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8875-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8877-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8878-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8879-1 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8875-2 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8917-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8918-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9003-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9024-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9025-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9026-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9029-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-9040-1 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9043-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9066-1 Linux kernel (HWE) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-122
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-122
Type Values Removed Values Added
Description 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.
Title nvme-multipath: fix flex array size in struct nvme_ns_head
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 16, 2026, 6:55 PM
Reserved
Aug 15, 2026, 5:44 AM
Status
Received
Published
Aug 15, 2026, 6:22 AM
Modified
Oct 16, 2026, 7:17 PM
Severity
Moderate
Public date
Aug 15, 2026, 12:00 AM