NFSv4.2 fix problems with __nfs42_ssc_open

A destination server while doing a COPY shouldn't accept using the
passed in filehandle if its not a regular filehandle.

If alloc_file_pseudo() has failed, we need to decrement a reference
on the newly created inode, otherwise it leaks.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: ec4b092 ("NFS: inter ssc open")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: olgakorn1

fs/nfs/nfs4file.c

@@ -340,6 +340,11 @@ static struct file *__nfs42_ssc_open(struct vfsmount *ss_mnt,
 		goto out;
 	}
 
+	if (!S_ISREG(fattr->mode)) {
+		res = ERR_PTR(-EBADF);
+		goto out;
+	}
+
 	res = ERR_PTR(-ENOMEM);
 	len = strlen(SSC_READ_NAME_BODY) + 16;
 	read_name = kzalloc(len, GFP_KERNEL);
@@ -357,6 +362,7 @@ static struct file *__nfs42_ssc_open(struct vfsmount *ss_mnt,
 				     r_ino->i_fop);
 	if (IS_ERR(filep)) {
 		res = ERR_CAST(filep);
+		iput(r_ino);
 		goto out_free_name;
 	}