Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before ca97360860eb02e3ae4ba42c19b439a0fcecbf06; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before e8bfa2401d4c51eca6e48e9b33c798828ca9df61; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before 34eb22836e0cdba093baac66599d68c4cd245a9d; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before 06600719d0f7a723811c45e4d51f5b742f345309; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before ba4811c8b433bfa681729ca42cc62b6034f223b0; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before 53f07d095e7e680c5e4569a55a019f2c0348cdc6; affected 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 before 2857bd59feb63fcf40fe4baf55401baea6b4feb4 |
| Linux / Linux | affected 3.18; unaffected 0 before 3.18; unaffected 5.10.248 through 5.10.*; unaffected 5.15.198 through 5.15.*; unaffected 6.1.161 through 6.1.*; unaffected 6.6.121 through 6.6.*; unaffected 6.12.66 through 6.12.*; unaffected 6.18.6 through 6.18.*; unaffected 6.19 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06
- https://git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61
- https://git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d
- https://git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309
- https://git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0
- https://git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6
- https://git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.