NFS - fix potential NULL pointer dereference v2

There is possible NULL pointer dereference if kstr[n]dup failed.
So fix them for safety.
Signed-off-by: NCyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -1297,6 +1297,8 @@ static int nfs_validate_mount_data(void *options,
 		args->namlen		= data->namlen;
 		args->bsize		= data->bsize;
 		args->auth_flavors[0]	= data->pseudoflavor;
+		if (!args->nfs_server.hostname)
+			goto out_nomem;
 
 		/*
 		 * The legacy version 6 binary mount data from userspace has a
@@ -1343,6 +1345,8 @@ static int nfs_validate_mount_data(void *options,
 		len = c - dev_name;
 		/* N.B. caller will free nfs_server.hostname in all cases */
 		args->nfs_server.hostname = kstrndup(dev_name, len, GFP_KERNEL);
+		if (!args->nfs_server.hostname)
+			goto out_nomem;
 
 		c++;
 		if (strlen(c) > NFS_MAXPATHLEN)
@@ -1386,6 +1390,10 @@ static int nfs_validate_mount_data(void *options,
 	return -EPROTONOSUPPORT;
 #endif /* !CONFIG_NFS_V3 */
 
+out_nomem:
+	dfprintk(MOUNT, "NFS: not enough memory to handle mount options\n");
+	return -ENOMEM;
+
 out_no_address:
 	dfprintk(MOUNT, "NFS: mount program didn't pass remote address\n");
 	return -EINVAL;
@@ -1892,12 +1900,16 @@ static int nfs4_validate_mount_data(void *options,
 			return -ENAMETOOLONG;
 		/* N.B. caller will free nfs_server.hostname in all cases */
 		args->nfs_server.hostname = kstrndup(dev_name, len, GFP_KERNEL);
+		if (!args->nfs_server.hostname)
+			goto out_nomem;
 
 		c++;			/* step over the ':' */
 		len = strlen(c);
 		if (len > NFS4_MAXPATHLEN)
 			return -ENAMETOOLONG;
 		args->nfs_server.export_path = kstrndup(c, len, GFP_KERNEL);
+		if (!args->nfs_server.export_path)
+			goto out_nomem;
 
 		dprintk("NFS: MNTPATH: '%s'\n", args->nfs_server.export_path);
 
@@ -1919,6 +1931,10 @@ static int nfs4_validate_mount_data(void *options,
 		 data->auth_flavourlen);
 	return -EINVAL;
 
+out_nomem:
+	dfprintk(MOUNT, "NFS4: not enough memory to handle mount options\n");
+	return -ENOMEM;
+
 out_no_address:
 	dfprintk(MOUNT, "NFS4: mount program didn't pass remote address\n");
 	return -EINVAL;