POSIX says you can use realloc() to shrink buffers ... make sure we dont trigger...

diff --git a/libc/stdlib/malloc-simple/alloc.c b/libc/stdlib/malloc-simple/alloc.c
index 321f319..6689ef4 100644 (file)
--- a/libc/stdlib/malloc-simple/alloc.c
+++ b/libc/stdlib/malloc-simple/alloc.c
@@ -91,7 +91,8 @@ void *realloc(void *ptr, size_t size)
 
        newptr = malloc(size);
        if (newptr) {
-               memcpy(newptr, ptr, *((size_t *) (ptr - sizeof(size_t))));
+               size_t old_size = *((size_t *) (ptr - sizeof(size_t)));
+               memcpy(newptr, ptr, (old_size < size ? old_size : size));
                free(ptr);
        }
        return newptr;