demux: mkv: fix use after free (cid #1049107)

GetMainName() can return a pointer to temporary string::

diff --git a/modules/demux/mkv/demux.cpp b/modules/demux/mkv/demux.cpp
index be20476cbe48c6cdb64018e9d34f5ed72ec62311..a0e8e89b5979ef349a5524fcf1789a18ea95ac03 100644 (file)
--- a/modules/demux/mkv/demux.cpp
+++ b/modules/demux/mkv/demux.cpp
@@ -684,9 +684,8 @@ bool demux_sys_t::PreloadLinked()
                 // TODO use a name for each edition, let the TITLE deal with a codec name
                 if ( p_title->psz_name == NULL )
                 {
-                    const char* psz_tmp = p_ved->GetMainName().c_str();
-                    if( *psz_tmp != '\0' )
-                        p_title->psz_name = strdup( psz_tmp );
+                    if( p_ved->GetMainName().length() )
+                        p_title->psz_name = strdup( p_ved->GetMainName().c_str() );
                     else
                     {
                         /* Check in tags if the edition has a name */