{"id":"CVE-2026-98150","summary":"bpf: Fix BPF_F_CPU validation for sparse CPU IDs","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix BPF_F_CPU validation for sparse CPU IDs\n\nBPF_F_CPU stores the target CPU ID in the upper 32 bits of the map\noperation flags. bpf_map_check_op_flags() currently compares that ID\nwith num_possible_cpus(), which is the number of possible CPUs rather\nthan a bound on CPU IDs.\n\nOn an arm64 QEMU guest with a CPU device-tree hole, the possible CPU\nmask was 0,2-3. A userspace program using raw bpf() syscalls creates\na BPF_MAP_TYPE_PERCPU_ARRAY and performs update and lookup operations\nfor each CPU by setting BPF_F_CPU and the CPU ID in the flags.\n\nWith the old check, CPU 1 is incorrectly accepted while valid CPU 3 is\nrejected with -ERANGE. The CPU 1 update then reaches the per-CPU map\naccess path and triggers:\n\n  Unable to handle kernel paging request at virtual address ...\n  pc : __pi_memcpy_generic+0x5c/0x22c\n  lr : bpf_percpu_array_update+0x2dc/0x2e8\n  Call trace:\n    __pi_memcpy_generic\n    bpf_map_update_value\n    map_update_elem\n    __sys_bpf\n\nCheck the CPU ID against nr_cpu_ids and cpu_possible() instead. This\nrejects CPU IDs outside the valid range and CPUs absent from the\npossible mask, while allowing valid sparse CPU IDs.","modified":"2026-09-26T03:48:37.235606251Z","published":"2026-09-25T10:36:22.774Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98150.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bdc5941f6eeef90b76a07fd8ca38ac1933ba2195"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ed54bf564ac52699cf4def3d0c2125d493e756f9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98150.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98150"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2b421662c7887a0649fe409155a1f101562d0fa9"},{"fixed":"bdc5941f6eeef90b76a07fd8ca38ac1933ba2195"},{"fixed":"ed54bf564ac52699cf4def3d0c2125d493e756f9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98150.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98150.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}