Merge branch 'zero-mem-on-malloc'

ChangeLog

@@ -21,7 +21,10 @@
 - add @reduction_effort param to webpsave [lovell]
 
 4/1/19 started 8.7.4
-- fix memory leak in magickload [kleisauke]
+- magickload with magick6 API did not chain exceptions correctly causing a
+  memory leak under some conditions [kleisauke]
+- zero memory on allocate to prevent write of uninitialized memory under some 
+  error conditions [Balint Varga-Perke]
 
 21/11/18 started 8.7.3
 - fix infinite loop for autofit with non-scaleable font 

libvips/iofuncs/memory.c

@@ -173,7 +173,7 @@ vips_malloc( VipsObject *object, size_t size )
 {
 	void *buf;
 
-	buf = g_malloc( size );
+	buf = g_malloc0( size );
 
         if( object ) {
 		g_signal_connect( object, "postclose", 
@@ -317,7 +317,7 @@ vips_tracked_malloc( size_t size )
 	 */
 	size += 16;
 
-        if( !(buf = g_try_malloc( size )) ) {
+        if( !(buf = g_try_malloc0( size )) ) {
 #ifdef DEBUG
 		g_assert_not_reached();
 #endif /*DEBUG*/