zero-initialize Client struct on allocation

Makefile

@@ -1,6 +1,7 @@
 CC=gcc
 EXT=.c
-FLAGS=-O0 -g -fsanitize=undefined -fsanitize=address
+FLAGS=-O0 -g
+DEBUG_FLAGS=-DDEBUG -fsanitize=undefined -fsanitize=address
 DEPFLAGS=-MD -MP
 LIBS=$(shell pkg-config --libs xcb x11 xinerama)
 EXEC_NAME=wm
@@ -26,7 +27,7 @@ $(OBJDIR)/%.o: $(SRCDIR)/%$(EXT)
 	$(CC) $(FLAGS) $(DEPFLAGS) -c -o $@ $<
 
 debug_flag:
-	$(eval FLAGS+=-DDEBUG)
+	$(eval FLAGS+=$(DEBUG_FLAGS))
 
 filter:
 	$(eval OBJS=$(filter-out obj/tests.o, $(OBJS)))

src/client.c

@@ -65,7 +65,7 @@ Client* wm_client_create(Wm *wm, Window w)
 
     XGetWMName(wm->display, w, &xtp);
 
-    Client *c = malloc(sizeof(Client));
+    Client *c = calloc(1, sizeof(Client));
 
     c->next = NULL;
     c->prev = NULL;