Link problem when using address sanitizer with android NDK - android-ndk

Question

I'm using Android Studio to build an app containing a module that uses the NDK. There is evidence of memory corruption so I'm trying the Address Sanitizer, following these instructions on the NDK developer site. But the app won't build.
I need to (A) ensure I'm targeting Android 27+ (I set minSdkVersion to 27; I'm building a debug build for a Galaxy S9, SDK 28), and (B) add compiler flags, which I've done:
android {
defaultConfig {
externalNativeBuild {
cmake {
# Can also use system or none as ANDROID_STL.
arguments "-DANDROID_ARM_MODE=arm", "-DANDROID_STL=c++_shared"
cppFlags "-fsanitize=address -fno-omit-frame-pointer"
}
}
}
}
I've also added wrap.sh scripts according to the instructions but I understand that they become relevant only at runtime.
The problem is that my app won't build. The output follows.
The C++ compiler
"C:/Users/user/AppData/Local/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe"
is not able to compile a simple test program.
It fails with the following output:
Change Dir:
C:/Users/user/studio/app/android/audioengine/.externalNativeBuild/cmake/debug/arm64-v8a/CMakeFiles/CMakeTmp
Run Build
Command:"C:\Users\user\AppData\Local\Android\sdk\cmake\3.6.4111459\bin\ninja.exe"
"cmTC_58655"
[1/2] Building CXX object
CMakeFiles/cmTC_58655.dir/testCXXCompiler.cxx.o
[2/2] Linking CXX executable cmTC_58655
FAILED: cmd.exe /C "cd . &&
C:\Users\user\AppData\Local\Android\sdk\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe
--target=aarch64-none-linux-android27 --gcc-toolchain=C:/Users/user/AppData/Local/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64
--sysroot=C:/Users/user/AppData/Local/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/sysroot
-g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -fno-addrsig -Wa,--noexecstack -Wformat -Werror=format-security -stdlib=libc++ -fsanitize=address -fno-omit-frame-pointer -Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libatomic.a -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--no-undefined -Qunused-arguments -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--gc-sections CMakeFiles/cmTC_58655.dir/testCXXCompiler.cxx.o -o cmTC_58655 -latomic -lm && cd ."
C:/Users/user/AppData/Local/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin\ld:
warning: liblog.so, needed by
C:\Users\tim\AppData\Local\Android\sdk\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\lib64\clang\8.0.2\lib\linux\libclang_rt.asan-aarch64-android.so,
not found (try using -rpath or -rpath-link)
clang++.exe: error: linker command failed with exit code 1 (use -v
to see invocation)
The compiler flags have been passed correctly. There is a warning concerning liblog.so not being found, but then a non-specific error.
The instructions show where to place the sanitizer libraries in the project (in the jniLibs folder), but not where to source them. I copied them from the NDK install on my machine. I tried doing the same with liblog libraries but It's not clear which variant to use; the one I tried (for SDK 28) didn't affect the result.
What am I missing? I've found posts struggling with understanding exactly how to use the address sanitizer, but none mentions this particular problem.

Answer 1

Looks like those docs are wrong. It seems that CMake isn't using all of the linker flags it needs when performing that test. I'm not sure if that's NDK bug or a CMake bug, but here's a way to make ASan work with CMake/gradle:
Remove the cppFlags section from your build.gradle
Add those options in your CMakeLists.txt instead, like so:
add_library(app SHARED app.cpp)
target_compile_options(app PUBLIC -fsanitize=address -fno-omit-frame-pointer)
set_target_properties(app PROPERTIES LINK_FLAGS -fsanitize=address)
I've uploaded a change to fix the docs. Should be live soon.