ghsa-vx82-qc8j-62qx
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()
There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use.
However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store().
============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted
syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415
but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215
other info that might help us debug this: Possible unsafe locking scenario:
CPU0
----
lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux);
*** DEADLOCK *** .... ============================================
The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use().
The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and all functions are already written this way. And in the function that uses ptp->n_vclocks, we already get ptp->n_vclocks_mux before unregistering vclocks.
Therefore, we need to remove the redundant check for ptp->n_vclocks in ptp_vclock_in_use() to prevent recursive locking.
{
"affected": [],
"aliases": [
"CVE-2025-38305"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-10T08:15:29Z",
"severity": null
},
"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 (\u0026ptp-\u003en_vclocks_mux){+.+.}-{4:4}, at:\n ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline]\nffff888035a24868 (\u0026ptp-\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 (\u0026ptp-\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(\u0026ptp-\u003en_vclocks_mux);\n lock(\u0026ptp-\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.",
"id": "GHSA-vx82-qc8j-62qx",
"modified": "2025-07-10T09:32:30Z",
"published": "2025-07-10T09:32:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38305"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
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