{"id":"CVE-2025-38305","summary":"ptp: remove ptp-\u003en_vclocks check logic in ptp_vclock_in_use()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nptp: remove ptp-\u003en_vclocks check logic in ptp_vclock_in_use()\n\nThere is no disagreement that we should check both ptp-\u003eis_virtual_clock\nand ptp-\u003en_vclocks to check if the ptp virtual clock is in use.\n\nHowever, when we acquire ptp-\u003en_vclocks_mux to read ptp-\u003en_vclocks in\nptp_vclock_in_use(), we observe a recursive lock in the call trace\nstarting from n_vclocks_store().\n\n============================================\nWARNING: possible recursive locking detected\n6.15.0-rc6 #1 Not tainted\n--------------------------------------------\nsyz.0.1540/13807 is trying to acquire lock:\nffff888035a24868 (&ptp-\u003en_vclocks_mux){+.+.}-{4:4}, at:\n ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline]\nffff888035a24868 (&ptp-\u003en_vclocks_mux){+.+.}-{4:4}, at:\n ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415\n\nbut task is already holding lock:\nffff888030704868 (&ptp-\u003en_vclocks_mux){+.+.}-{4:4}, at:\n n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215\n\nother info that might help us debug this:\n Possible unsafe locking scenario:\n\n       CPU0\n       ----\n  lock(&ptp-\u003en_vclocks_mux);\n  lock(&ptp-\u003en_vclocks_mux);\n\n *** DEADLOCK ***\n....\n============================================\n\nThe best way to solve this is to remove the logic that checks\nptp-\u003en_vclocks in ptp_vclock_in_use().\n\nThe reason why this is appropriate is that any path that uses\nptp-\u003en_vclocks must unconditionally check if ptp-\u003en_vclocks is greater\nthan 0 before unregistering vclocks, and all functions are already\nwritten this way. And in the function that uses ptp-\u003en_vclocks, we\nalready get ptp-\u003en_vclocks_mux before unregistering vclocks.\n\nTherefore, we need to remove the redundant check for ptp-\u003en_vclocks in\nptp_vclock_in_use() to prevent recursive locking.","modified":"2026-04-16T04:33:36.595460907Z","published":"2025-07-10T07:42:16.127Z","related":["SUSE-SU-2025:02853-1","SUSE-SU-2025:02923-1","SUSE-SU-2025:02969-1","SUSE-SU-2025:02996-1","SUSE-SU-2025:02997-1","SUSE-SU-2025:03011-1","SUSE-SU-2025:03023-1","SUSE-SU-2025:20577-1","SUSE-SU-2025:20586-1","SUSE-SU-2025:20601-1","SUSE-SU-2025:20602-1","SUSE-SU-2025:21074-1","SUSE-SU-2025:21139-1","SUSE-SU-2025:21179-1","openSUSE-SU-2025:20081-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38305.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/259119595227fd20f6aa29d85abe086b6fdd9eb1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5d217e7031a5c06d366580fc6ddbf43527b780d4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/87f7ce260a3c838b49e1dc1ceedf1006795157a2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b1b73c452331451020be3bf4b014901015ae6663"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b93e6fef4eda48e17d9c642b9abad98a066fd4a3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ef8fc007c28a30a4c0d90bf755e0f343d99bb392"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38305.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38305"},{"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":"73f37068d540eba5f93ba3a0019bf479d35ebd76"},{"fixed":"5d217e7031a5c06d366580fc6ddbf43527b780d4"},{"fixed":"b1b73c452331451020be3bf4b014901015ae6663"},{"fixed":"259119595227fd20f6aa29d85abe086b6fdd9eb1"},{"fixed":"b93e6fef4eda48e17d9c642b9abad98a066fd4a3"},{"fixed":"ef8fc007c28a30a4c0d90bf755e0f343d99bb392"},{"fixed":"87f7ce260a3c838b49e1dc1ceedf1006795157a2"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38305.json"}}],"schema_version":"1.7.5"}