cifs: fix memory leak in SMB2_read

commit 05fd5c2c upstream.

Commit 088aaf17 introduced a leak where
if SMB2_read() returned an error we would return without freeing the
request buffer.

Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/cifs/smb2pdu.c

@@ -3285,6 +3285,7 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
 					    rc);
 		}
 		free_rsp_buf(resp_buftype, rsp_iov.iov_base);
+		cifs_small_buf_release(req);
 		return rc == -ENODATA ? 0 : rc;
 	} else
 		trace_smb3_read_done(xid, req->PersistentFileId,