Handle early termination properly in StripTags

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 2b790c3e8cbc3dfb7e8709027b7bea358c6f18ba)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/subtitles/subsdec.c

@@ -632,6 +632,9 @@ static char *StripTags( char *psz_subtitle )
             *psz_text++ = *psz_subtitle;
         }
 
+        /* Security fix: Account for the case where input ends early */
+        if( *psz_subtitle == '\0' ) break;
+
         psz_subtitle++;
     }
     *psz_text = '\0';

modules/codec/subtitles/subsusf.c

@@ -1081,6 +1081,9 @@ static char *StripTags( char *psz_subtitle )
             *psz_text++ = *psz_subtitle;
         }
 
+        /* Security fix: Account for the case where input ends early */
+        if( *psz_subtitle == '\0' ) break;
+
         psz_subtitle++;
     }
     *psz_text = '\0';