{"id":"CVE-2025-21910","summary":"wifi: cfg80211: regulatory: improve invalid hints checking","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: cfg80211: regulatory: improve invalid hints checking\n\nSyzbot keeps reporting an issue [1] that occurs when erroneous symbols\nsent from userspace get through into user_alpha2[] via\nregulatory_hint_user() call. Such invalid regulatory hints should be\nrejected.\n\nWhile a sanity check from commit 47caf685a685 (\"cfg80211: regulatory:\nreject invalid hints\") looks to be enough to deter these very cases,\nthere is a way to get around it due to 2 reasons.\n\n1) The way isalpha() works, symbols other than latin lower and\nupper letters may be used to determine a country/domain.\nFor instance, greek letters will also be considered upper/lower\nletters and for such characters isalpha() will return true as well.\nHowever, ISO-3166-1 alpha2 codes should only hold latin\ncharacters.\n\n2) While processing a user regulatory request, between\nreg_process_hint_user() and regulatory_hint_user() there happens to\nbe a call to queue_regulatory_request() which modifies letters in\nrequest-\u003ealpha2[] with toupper(). This works fine for latin symbols,\nless so for weird letter characters from the second part of _ctype[].\n\nSyzbot triggers a warning in is_user_regdom_saved() by first sending\nover an unexpected non-latin letter that gets malformed by toupper()\ninto a character that ends up failing isalpha() check.\n\nPrevent this by enhancing is_an_alpha2() to ensure that incoming\nsymbols are latin letters and nothing else.\n\n[1] Syzbot report:\n------------[ cut here ]------------\nUnexpected user alpha2: A�\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\nModules linked in:\nCPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: events_power_efficient crda_timeout_work\nRIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline]\nRIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline]\nRIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\n...\nCall Trace:\n \u003cTASK\u003e\n crda_timeout_work+0x27/0x50 net/wireless/reg.c:542\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f2/0x390 kernel/kthread.c:389\n ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n \u003c/TASK\u003e","modified":"2026-03-20T12:41:14.067879Z","published":"2025-04-01T15:40:49.189Z","related":["SUSE-SU-2025:01600-1","SUSE-SU-2025:01614-1","SUSE-SU-2025:01707-1","SUSE-SU-2025:01919-1","SUSE-SU-2025:01951-1","SUSE-SU-2025:01964-1","SUSE-SU-2025:01967-1","SUSE-SU-2025:20192-1","SUSE-SU-2025:20206-1","SUSE-SU-2025:20270-1","SUSE-SU-2025:20283-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21910.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/17aa34c84867f6cd181a5743e1c647e7766962a6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/35ef07112b61b06eb30683a6563c9f6378c02476"},{"type":"WEB","url":"https://git.kernel.org/stable/c/59b348be7597c4a9903cb003c69e37df20c04a30"},{"type":"WEB","url":"https://git.kernel.org/stable/c/62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6a5e3b23054cee3b92683d1467e3fa83921f5622"},{"type":"WEB","url":"https://git.kernel.org/stable/c/be7c5f00aa7f1344293e4d48d0e12be83a2f223d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/da3f599517ef2ea851208df3229d07728d238dc5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f4112cb477c727a65787a4065a75ca593bb5b2f4"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21910.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21910"},{"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":"09d989d179d0c679043556dda77c51b41a2dae7e"},{"fixed":"62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6"},{"fixed":"da3f599517ef2ea851208df3229d07728d238dc5"},{"fixed":"6a5e3b23054cee3b92683d1467e3fa83921f5622"},{"fixed":"f4112cb477c727a65787a4065a75ca593bb5b2f4"},{"fixed":"35ef07112b61b06eb30683a6563c9f6378c02476"},{"fixed":"be7c5f00aa7f1344293e4d48d0e12be83a2f223d"},{"fixed":"17aa34c84867f6cd181a5743e1c647e7766962a6"},{"fixed":"59b348be7597c4a9903cb003c69e37df20c04a30"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21910.json"}}],"schema_version":"1.7.5"}