Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix possible badness in FREE_STATEID
When multiple FREE_STATEIDs are sent for the same delegation stateid, it can lead to a possible either use-after-free or counter refcount underflow errors.
In nfsd4_free_stateid() under the client lock we find a delegation stateid, however the code drops the lock before calling nfs4_put_stid(), that allows another FREE_STATE to find the stateid again. The first one will proceed to then free the stateid which leads to either use-after-free or decrementing already zeroed counter.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS
- Affected packages:
- kernel @ 4.18.0 (+2 more)
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix possible badness in FREE_STATEID
When multiple FREE_STATEIDs are sent for the same delegation stateid, it can lead to a possible either use-after-free or counter refcount underflow errors.
In nfsd4_free_stateid() under the client lock we find a delegation stateid, however the code drops the lock before calling nfs4_put_stid(), that allows another FREE_STATE to find the stateid again. The first one will proceed to then free the stateid which leads to either use-after-free or decrementing already zeroed counter.