{"id":"CVE-2025-21851","summary":"bpf: Fix softlockup in arena_map_free on 64k page kernel","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix softlockup in arena_map_free on 64k page kernel\n\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup.\nThe same failure is not observed with 4k pages on aarch64.\n\nIt turns out arena_map_free() is calling\napply_to_existing_page_range() with the address returned by\nbpf_arena_get_kern_vm_start().  If this address is not page-aligned\nthe code ends up calling apply_to_pte_range() with that unaligned\naddress causing soft lockup.\n\nFix it by round up GUARD_SZ to PAGE_SIZE \u003c\u003c 1 so that the\ndivision by 2 in bpf_arena_get_kern_vm_start() returns\na page-aligned value.","modified":"2026-04-02T12:45:15.192623Z","published":"2025-03-12T09:42:06.480Z","related":["ALSA-2025:20095","ALSA-2025:20518","USN-7521-2"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21851.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21851.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21851"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"317460317a02a1af512697e6e964298dedd8a163"},{"fixed":"c1f3f3892d4526f18aaeffdb6068ce861e793ee3"},{"fixed":"787d556a3de447e70964a4bdeba9196f62a62b1e"},{"fixed":"517e8a7835e8cfb398a0aeb0133de50e31cae32b"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21851.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"}]}