Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:[EOL][EOL]nfsd: fix refcount leak in nfsd_set_fh_dentry()[EOL][EOL]nfsd exports a "pseudo root filesystem" which is used by NFSv4 to find[EOL]the various exported filesystems using LOOKUP requests from a known root[EOL]filehandle.  NFSv3 uses the MOUNT protocol to find those exported[EOL]filesystems and so is not given access to the pseudo root filesystem.[EOL][EOL]If a v3 (or v2) client uses a filehandle from that filesystem,[EOL]nfsd_set_fh_dentry() will report an error, but still stores the export[EOL]in "struct svc_fh" even though it also drops the reference (exp_put()).[EOL]This means that when fh_put() is called an extra reference will be dropped[EOL]which can lead to use-after-free and possible denial of service.[EOL][EOL]Normal NFS usage will not provide a pseudo-root filehandle to a v3[EOL]client.  This bug can only be triggered by the client synthesising an[EOL]incorrect filehandle.[EOL][EOL]To fix this we move the assignments to the svc_fh later, after all[EOL]possible error cases have been detected.