{"cve":"CVE-2025-38305","nvd":{"published":"2025-07-10T08:15:29.320","modified":"2026-06-17T09:16:35.237","status":"Analyzed","description":"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 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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/259119595227fd20f6aa29d85abe086b6fdd9eb1","https://git.kernel.org/stable/c/5d217e7031a5c06d366580fc6ddbf43527b780d4","https://git.kernel.org/stable/c/87f7ce260a3c838b49e1dc1ceedf1006795157a2","https://git.kernel.org/stable/c/b1b73c452331451020be3bf4b014901015ae6663","https://git.kernel.org/stable/c/b93e6fef4eda48e17d9c642b9abad98a066fd4a3"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:04:28.436527499+00:00"},"epss":{"cve":"CVE-2025-38305","score":0.00178,"percentile":0.07365,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}