{"id":"AZL-64961","summary":"CVE-2025-38305 affecting package kernel for versions less than 6.6.96.1-1","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":"2026-04-21T04:32:37.646829Z","published":"2025-07-10T08:15:29Z","upstream":["CVE-2025-38305"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38305"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.96.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-64961.json"}}],"schema_version":"1.7.5"}