SMB3: GUIDs should be constructed as random but valid uuids

commit fa70b87c upstream.

GUIDs although random, and 16 bytes, need to be generated as
proper uuids.
Signed-off-by: Steve French <steve.french@primarydata.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reported-by: David Goebels <davidgoe@microsoft.com>
[bwh: Backported to 3.16: drop changes to create_durable_v2_buf()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/cifs/cifsfs.c

@@ -256,7 +256,7 @@ cifs_alloc_inode(struct super_block *sb)
 	cifs_inode->createtime = 0;
 	cifs_inode->epoch = 0;
 #ifdef CONFIG_CIFS_SMB2
-	get_random_bytes(cifs_inode->lease_key, SMB2_LEASE_KEY_SIZE);
+	generate_random_uuid(cifs_inode->lease_key);
 #endif
 	/*
 	 * Can not set i_flags here - they get immediately overwritten to zero

fs/cifs/connect.c

@@ -2147,7 +2147,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	memcpy(&tcp_ses->dstaddr, &volume_info->dstaddr,
 		sizeof(tcp_ses->dstaddr));
 #ifdef CONFIG_CIFS_SMB2
-	get_random_bytes(tcp_ses->client_guid, SMB2_CLIENT_GUID_SIZE);
+	generate_random_uuid(tcp_ses->client_guid);
 #endif
 	/*
 	 * at this point we are the only ones with the pointer

fs/cifs/smb2ops.c

@@ -855,7 +855,7 @@ smb2_set_lease_key(struct inode *inode, struct cifs_fid *fid)
 static void
 smb2_new_lease_key(struct cifs_fid *fid)
 {
-	get_random_bytes(fid->lease_key, SMB2_LEASE_KEY_SIZE);
+	generate_random_uuid(fid->lease_key);
 }
 
 #define SMB2_SYMLINK_STRUCT_SIZE \