memory leak example

README.adoc

@@ -12857,7 +12857,9 @@ Allocate memory! Vs using the stack: https://stackoverflow.com/questions/4584089
 
 link:userland/c/malloc.c[]: `malloc` hello world: allocate two ints and use them.
 
-LInux 5.1 / glibc 2.29 implements it with the <<mmap,`mmap` system call>>.
+Linux 5.1 / glibc 2.29 implements it with the <<mmap,`mmap` system call>>.
+
+`malloc` leads to the infinite joys of <<memory-leaks>>.
 
 ===== malloc implementation
 
@@ -13125,7 +13127,15 @@ Let's group the hard-to-debug undefined-behaviour-like stuff found in C / C+ her
 
 https://stackoverflow.com/questions/1345670/stack-smashing-detected/51897264#51897264
 
-link:userland/c/smash_stack.c[]
+Example:: link:userland/c/smash_stack.c[]
+
+Leads to the dreadful "Stack smashing detected" message. Which is infinitely better than a silent break in any case.
+
+==== Memory leaks
+
+How to debug: https://stackoverflow.com/questions/6261201/how-to-find-memory-leak-in-a-c-code-project/57877190#57877190
+
+Example: link:userland/c/memory_leak.c[]
 
 === Userland content bibliography
 

userland/c/memory_leak.c

@@ -0,0 +1,23 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#memory-leaks */
+
+#include <stdlib.h>
+
+void * my_malloc(size_t n) {
+    return malloc(n);
+}
+
+void leaky(size_t n, int do_leak) {
+    void *p = my_malloc(n);
+    if (!do_leak) {
+        free(p);
+    }
+}
+
+int main(void) {
+    leaky(0x10, 0);
+    leaky(0x10, 1);
+    leaky(0x100, 0);
+    leaky(0x100, 1);
+    leaky(0x1000, 0);
+    leaky(0x1000, 1);
+}