NFSd: Fix filehandle leak in exp_pseudoroot() and nfsd4_path()

nfsd4_path() allocates a temporary filehandle and then fails to free it
before the function exits, leaking reference counts to the dentry and
export that it refers to.

Also, nfsd4_lookupp() puts the result of exp_pseudoroot() in a temporary
filehandle which it releases on success of exp_pseudoroot() but not on
failure; fix exp_pseudoroot to ensure that on failure it releases the
filehandle before returning.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/export.c

@@ -1341,6 +1341,8 @@ exp_pseudoroot(struct svc_rqst *rqstp, struct svc_fh *fhp)
 	if (rv)
 		goto out;
 	rv = check_nfsd_access(exp, rqstp);
+	if (rv)
+		fh_put(fhp);
 out:
 	exp_put(exp);
 	return rv;

fs/nfsd/nfs4xdr.c

@@ -1599,7 +1599,8 @@ static __be32 nfsd4_encode_fs_location4(struct nfsd4_fs_location *location,
 static char *nfsd4_path(struct svc_rqst *rqstp, struct svc_export *exp, __be32 *stat)
 {
 	struct svc_fh tmp_fh;
-	char *path, *rootpath;
+	char *path = NULL, *rootpath;
+	size_t rootlen;
 
 	fh_init(&tmp_fh, NFS4_FHSIZE);
 	*stat = exp_pseudoroot(rqstp, &tmp_fh);
@@ -1609,14 +1610,18 @@ static char *nfsd4_path(struct svc_rqst *rqstp, struct svc_export *exp, __be32 *
 
 	path = exp->ex_pathname;
 
-	if (strncmp(path, rootpath, strlen(rootpath))) {
+	rootlen = strlen(rootpath);
+	if (strncmp(path, rootpath, rootlen)) {
 		dprintk("nfsd: fs_locations failed;"
 			"%s is not contained in %s\n", path, rootpath);
 		*stat = nfserr_notsupp;
-		return NULL;
+		path = NULL;
+		goto out;
 	}
-
-	return path + strlen(rootpath);
+	path += rootlen;
+out:
+	fh_put(&tmp_fh);
+	return path;
 }
 
 /*