Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

NFS: Pin the 'struct nfs_server' during a FREE_STATEID call

Dan Aloni reports that he was able to hit a use-after-free bug if a FREE_STATEID operation gets delayed for whatever reason. Fix this by bumping the refcount of the 'struct nfs_server' object for the duration of the FREE_STATEID so it doesn't get cleaned up from underneath us while operations are still in flight.