Address Sanitizer

The Android NDK supports Address Sanitizer beginning with API level 27 (Android O MR 1).

ASan is a fast compiler-based tool for detecting memory bugs in native code. ASan detects:

  • Stack and heap buffer overflow/underflow
  • Heap use after free
  • Stack use outside scope
  • Double free/wild free

ASan runs on both 32-bit and 64-bit ARM, plus x86 and x86-64. ASan's CPU overhead is roughly 2x, code size overhead is between 50% and 2x, and the memory overhead is large (dependent on your allocation patterns, but on the order of 2x).

For 64-bit ARM, HWASan may be a better choice.


To build your app's native (JNI) code with Address Sanitizer, do the following:


In your

APP_STL := c++_shared # Or system, or none.
APP_CFLAGS := -fsanitize=address -fno-omit-frame-pointer
APP_LDFLAGS := -fsanitize=address

For each module in your



In your module's build.gradle:

android {
    defaultConfig {
        externalNativeBuild {
            cmake {
                # Can also use system or none as ANDROID_STL.
                arguments "-DANDROID_ARM_MODE=arm", "-DANDROID_STL=c++_shared"

For each target in your CMakeLists.txt:

target_compile_options(${TARGET} PUBLIC -fsanitize=address -fno-omit-frame-pointer)
set_target_properties(${TARGET} PROPERTIES LINK_FLAGS -fsanitize=address)


Beginning with Android O MR1 (API level 27) an application can provide a script that can wrap or replace the application process. This allows a debuggable application to customize their application startup, which enables using ASan on production devices.

  1. Add android:debuggable to the application manifest.
  2. Add the ASan runtime library to your app module's jniLibs.
  3. Add files with the following contents to each of the same directories.

    HERE="$(cd "$(dirname "$0")" && pwd)"
    export ASAN_OPTIONS=log_to_syslog=false,allow_user_segv_handler=1
    ASAN_LIB=$(ls $HERE/libclang_rt.asan-*
    if [ -f "$HERE/" ]; then
        # Workaround for
        export LD_PRELOAD="$ASAN_LIB $HERE/"
        export LD_PRELOAD="$ASAN_LIB"

Assuming your project's application module is named app, your final directory structure should include the following:

<project root>
└── app
    └── src
        └── main
            ├── jniLibs
            │   ├── arm64-v8a
            │   │   └──
            │   ├── armeabi-v7a
            │   │   └──
            │   ├── x86
            │   │   └──
            │   └── x86_64
            │       └──
            └── resources
                └── lib
                    ├── arm64-v8a
                    │   └──
                    ├── armeabi-v7a
                    │   └──
                    ├── x86
                    │   └──
                    └── x86_64

Stack traces

Address Sanitizer needs to unwind the stack on every malloc/realloc/free call. There are two options here:

  1. A "fast" frame pointer-based unwinder. This is what is used by following the instructions in the building section.

  2. A "slow" CFI unwinder. In this mode ASan uses _Unwind_Backtrace. It requires only -funwind-tables, which is normally enabled by default.

The fast unwinder is the default for malloc/realloc/free. The slow unwinder is the default for fatal stack traces. The slow unwinder can be enabled for all stack traces by adding fast_unwind_on_malloc=0 to the ASAN_OPTIONS variable in your