Description (CNA)
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 (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before 5d217e7031a5c06d366580fc6ddbf43527b780d4; affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before b1b73c452331451020be3bf4b014901015ae6663; affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before 259119595227fd20f6aa29d85abe086b6fdd9eb1; affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before b93e6fef4eda48e17d9c642b9abad98a066fd4a3; affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before ef8fc007c28a30a4c0d90bf755e0f343d99bb392; affected 73f37068d540eba5f93ba3a0019bf479d35ebd76 before 87f7ce260a3c838b49e1dc1ceedf1006795157a2 |
| Linux / Linux | affected 5.14; unaffected 0 before 5.14; unaffected 5.15.186 through 5.15.*; unaffected 6.1.142 through 6.1.*; unaffected 6.6.94 through 6.6.*; unaffected 6.12.34 through 6.12.*; unaffected 6.15.3 through 6.15.*; unaffected 6.16 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/5d217e7031a5c06d366580fc6ddbf43527b780d4
- https://git.kernel.org/stable/c/b1b73c452331451020be3bf4b014901015ae6663
- https://git.kernel.org/stable/c/259119595227fd20f6aa29d85abe086b6fdd9eb1
- https://git.kernel.org/stable/c/b93e6fef4eda48e17d9c642b9abad98a066fd4a3
- https://git.kernel.org/stable/c/ef8fc007c28a30a4c0d90bf755e0f343d99bb392
- https://git.kernel.org/stable/c/87f7ce260a3c838b49e1dc1ceedf1006795157a2
ADP enrichment
No English description supplied.