CVE-2026-74384
NVD analysis in progress
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.
What this means
- Exposure
- Exploitable remotely over the network, without authentication and with no action from the victim.
- Impact
- An attacker can read sensitive data, modify or destroy data and take the service offline.
- Likelihood
- Its EPSS score stays low: nothing points to imminent exploitation, which is no reason to leave it unpatched.
What to doPatch without waiting for the next scheduled cycle. Start with the instances exposed to the internet.
Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.