{"id":"CVE-2025-38305","title":"ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()\n\nThere is no disagreement that we should check both ptp->is_virtual_clock\nand ptp->n_vclocks to check if t…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 5d217e7031a5c06d366580fc6ddbf43527b780d4","Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < b1b73c452331451020be3bf4b014901015ae6663","Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 259119595227fd20f6aa29d85abe086b6fdd9eb1","Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < b93e6fef4eda48e17d9c642b9abad98a066fd4a3","Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < ef8fc007c28a30a4c0d90bf755e0f343d99bb392","Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 87f7ce260a3c838b49e1dc1ceedf1006795157a2","Linux 5.14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T20:53:36.196517Z"},"published":"2025-07-10","updated":"2026-11-05","sourceUpdated":"2026-11-05T21:02:31.571Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-38305","references":[{"url":"https://git.kernel.org/stable/c/5d217e7031a5c06d366580fc6ddbf43527b780d4"},{"url":"https://git.kernel.org/stable/c/b1b73c452331451020be3bf4b014901015ae6663"},{"url":"https://git.kernel.org/stable/c/259119595227fd20f6aa29d85abe086b6fdd9eb1"},{"url":"https://git.kernel.org/stable/c/b93e6fef4eda48e17d9c642b9abad98a066fd4a3"},{"url":"https://git.kernel.org/stable/c/ef8fc007c28a30a4c0d90bf755e0f343d99bb392"},{"url":"https://git.kernel.org/stable/c/87f7ce260a3c838b49e1dc1ceedf1006795157a2"}],"tags":["cve.org"],"epss":0.00179,"epssPercentile":0.07516,"ingestedAt":"2026-11-05T22:38:31.949Z","slug":"CVE-2025-38305","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()\n\nThere is no disagreement that we should check both ptp->is_virtual_clock\nand ptp->n_vclocks to check if the ptp virtual clock is in use.\n\nHowever, when we acquire ptp->n_vclocks_mux to read ptp->n_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->n_vclocks_mux){+.+.}-{4:4}, at:\n ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline]\nffff888035a24868 (&ptp->n_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->n_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->n_vclocks_mux);\n  lock(&ptp->n_vclocks_mux);\n\n *** DEADLOCK ***\n....\n============================================\n\nThe best way to solve this is to remove the logic that checks\nptp->n_vclocks in ptp_vclock_in_use().\n\nThe reason why this is appropriate is that any path that uses\nptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater\nthan 0 before unregistering vclocks, and all functions are already\nwritten this way. And in the function that uses ptp->n_vclocks, we\nalready get ptp->n_vclocks_mux before unregistering vclocks.\n\nTherefore, we need to remove the redundant check for ptp->n_vclocks in\nptp_vclock_in_use() to prevent recursive locking.\n\n## Affected\n\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 5d217e7031a5c06d366580fc6ddbf43527b780d4`\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < b1b73c452331451020be3bf4b014901015ae6663`\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 259119595227fd20f6aa29d85abe086b6fdd9eb1`\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < b93e6fef4eda48e17d9c642b9abad98a066fd4a3`\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < ef8fc007c28a30a4c0d90bf755e0f343d99bb392`\n- `Linux >= 73f37068d540eba5f93ba3a0019bf479d35ebd76 < 87f7ce260a3c838b49e1dc1ceedf1006795157a2`\n- `Linux 5.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}