66 lines · cpp
1// RUN: %clang_asan -O2 %s -o %t2// RUN: %run %t 2>&1 | FileCheck --check-prefix=CHECK-NOSCRIBBLE %s3// RUN: %env MallocScribble=1 MallocPreScribble=1 %run %t 2>&1 | FileCheck --check-prefix=CHECK-SCRIBBLE %s4// RUN: %env_asan_opts=max_free_fill_size=4096 %run %t 2>&1 | FileCheck --check-prefix=CHECK-SCRIBBLE %s5 6#include <stdint.h>7#include <stdio.h>8#include <stdlib.h>9#include <string.h>10 11struct Isa {12 const char *class_name;13};14 15struct MyClass {16 // User memory and `ChunkHeader` overlap. In particular the `free_context_id`17 // is stored at the beginning of user memory when it is freed. That part of18 // user memory is not scribbled and is changed when the memory is freed. This19 // test relies on `isa` being scribbled or unmodified after memory is freed.20 // In order for this to work the start of `isa` must come after whatever is in21 // `ChunkHeader` (currently the 64-bit `free_context_id`). The padding here is22 // to ensure this is the case.23 uint64_t padding;24 Isa *isa;25 long data;26 27 void print_my_class_name();28};29 30__attribute__((no_sanitize("address")))31void MyClass::print_my_class_name() {32 fprintf(stderr, "this = %p\n", this);33 fprintf(stderr, "padding = 0x%lx\n", this->padding);34 fprintf(stderr, "isa = %p\n", this->isa);35 36 if ((uint32_t)(uintptr_t)this->isa != 0x55555555) {37 fprintf(stderr, "class name: %s\n", this->isa->class_name);38 }39}40 41int main() {42 Isa *my_class_isa = (Isa *)malloc(sizeof(Isa));43 memset(my_class_isa, 0x77, sizeof(Isa));44 my_class_isa->class_name = "MyClass";45 46 MyClass *my_object = (MyClass *)malloc(sizeof(MyClass));47 memset(my_object, 0x88, sizeof(MyClass));48 my_object->isa = my_class_isa;49 my_object->data = 42;50 51 my_object->print_my_class_name();52 // CHECK-SCRIBBLE: class name: MyClass53 // CHECK-NOSCRIBBLE: class name: MyClass54 55 free(my_object);56 57 my_object->print_my_class_name();58 // CHECK-NOSCRIBBLE: class name: MyClass59 // CHECK-SCRIBBLE: isa = {{(0x)?}}{{5555555555555555|55555555}}60 61 fprintf(stderr, "okthxbai!\n");62 // CHECK-SCRIBBLE: okthxbai!63 // CHECK-NOSCRIBBLE: okthxbai!64 free(my_class_isa);65}66