demux: ogg: check ogg_sync_buffer allocs

(cherry picked from commit 03100bbd06)

modules/demux/ogg.c

@@ -987,6 +987,8 @@ static int Ogg_ReadPage( demux_t *p_demux, ogg_page *p_oggpage )
     while( ogg_sync_pageout( &p_ogg->oy, p_oggpage ) != 1 )
     {
         p_buffer = ogg_sync_buffer( &p_ogg->oy, OGGSEEK_BYTES_TO_READ );
+        if( !p_buffer )
+            return VLC_EGENERIC;
 
         i_read = vlc_stream_Read( p_demux->s, p_buffer, OGGSEEK_BYTES_TO_READ );
         if( i_read <= 0 )

modules/demux/oggseek.c

@@ -204,6 +204,8 @@ static int64_t get_data( demux_t *p_demux, int64_t i_bytes_to_read )
     seek_byte ( p_demux, p_sys->i_input_position );
 
     buf = ogg_sync_buffer( &p_sys->oy, i_bytes_to_read );
+    if( !buf )
+        return 0;
 
     i_result = vlc_stream_Read( p_demux->s, buf, i_bytes_to_read );
 
@@ -1093,6 +1095,8 @@ int64_t oggseek_read_page( demux_t *p_demux )
     ogg_sync_reset( &p_ogg->oy );
 
     buf = ogg_sync_buffer( &p_ogg->oy, i_page_size );
+    if( !buf )
+        return 0;
 
     memcpy( buf, header, PAGE_HEADER_BYTES + i_nsegs );