Compiling with Address Sanitizer (ASAN) with CLANG and with GCC-4.8

README.md

Readme

This is a demo that shows how to configure GCC and Clang to build and run with the address sanitizer instrumented code.

You need the ASAN_OPTIONS=symbolize=1 to turn on resolving addresses in object code to source code line numbers and filenames. This option is implicit for Clang but it won't do any harm.

The recommended way for GCC is to statically link against ASAN using -static-libasan. See the ldd output.

main.cpp

// this causes a stack-buffer-overflow
int main(int argc, char **argv) {
  int stack_array[100];
  stack_array[1] = 0;
  return stack_array[argc + 100];  // BOOM
}

Makefile

.PHONY: using-gcc using-gcc-static using-clang

using-gcc:
	g++-4.8 -o main-gcc -lasan -O -g -fsanitize=address -fno-omit-frame-pointer main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=$(shell which llvm-symbolizer) ./main-gcc

using-gcc-static:
	g++-4.8 -o main-gcc-static -static-libstdc++ -static-libasan -O -g -fsanitize=address -fno-omit-frame-pointer main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=$(shell which llvm-symbolizer) ./main-gcc-static

using-clang:
	clang -o main-clang -x c++ -O -g -fsanitize=address main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=$(shell which llvm-symbolizer) ./main-clang

output_of_make_using-clang

$ make using-clang 
clang -o main-clang -x c++ -O -g -fsanitize=address main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=/usr/local/bin/llvm-symbolizer ./main-clang
=================================================================
==25497==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffaeb43014 at pc 0x4b7453 bp 0x7fffaeb42e50 sp 0x7fffaeb42e48
READ of size 4 at 0x7fffaeb43014 thread T0
    #0 0x4b7452 in main /home/kkleine/Development/asan-test/main.cpp:5
    #1 0x2af489d27ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287
    #2 0x4b720c in _start (/home/kkleine/Development/asan-test/main-clang+0x4b720c)

Address 0x7fffaeb43014 is located in stack of thread T0 at offset 436 in frame
    #0 0x4b72ef in main /home/kkleine/Development/asan-test/main.cpp:2

  This frame has 1 object(s):
    [32, 432) 'stack_array' <== Memory access at offset 436 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/kkleine/Development/asan-test/main.cpp:5 main
Shadow bytes around the buggy address:
  0x100075d605b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d605c0: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
  0x100075d605d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d605e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d605f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x100075d60600: 00 00[f3]f3 f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00
  0x100075d60610: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d60620: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d60630: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d60640: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100075d60650: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  ASan internal:           fe
==25497==ABORTING
make: *** [using-clang] Error 1

output_of_make_using-gcc

$ make using-gcc
g++-4.8 -o main-gcc -lasan -O -g -fsanitize=address -fno-omit-frame-pointer main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=/usr/local/bin/llvm-symbolizer ./main-gcc
=================================================================
==25394== ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffd708a284 at pc 0x40080d bp 0x7fffd708a0c0 sp 0x7fffd708a0b8
READ of size 4 at 0x7fffd708a284 thread T0
    #0 0x40080c in main /home/kkleine/Development/asan-test/main.cpp:5
    #1 0x2b9e16013ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287
    #2 0x400688 in _start (/home/kkleine/Development/asan-test/main-gcc+0x400688)
Address 0x7fffd708a284 is located at offset 436 in frame <main> of T0's stack:
  This frame has 1 object(s):
    [32, 432) 'stack_array'
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/kkleine/Development/asan-test/main.cpp:5 main
Shadow bytes around the buggy address:
  0x10007ae09400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09410: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00
  0x10007ae09420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10007ae09450:[f4]f4 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
  0x10007ae09460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae09490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007ae094a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:     fa
  Heap righ redzone:     fb
  Freed Heap region:     fd
  Stack left redzone:    f1
  Stack mid redzone:     f2
  Stack right redzone:   f3
  Stack partial redzone: f4
  Stack after return:    f5
  Stack use after scope: f8
  Global redzone:        f9
  Global init order:     f6
  Poisoned by user:      f7
  ASan internal:         fe
==25394== ABORTING
make: *** [using-gcc] Error 1

output_of_make_using-gcc-static

$ make using-gcc-static 
g++-4.8 -o main-gcc-static -static-libstdc++ -static-libasan -O -g -fsanitize=address -fno-omit-frame-pointer main.cpp && \
	ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=/usr/local/bin/llvm-symbolizer ./main-gcc-static
=================================================================
==25464== ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fff8f79d214 at pc 0x41ab0b bp 0x7fff8f79d050 sp 0x7fff8f79d048
READ of size 4 at 0x7fff8f79d214 thread T0
    #0 0x41ab0a in main /home/kkleine/Development/asan-test/main.cpp:5
    #1 0x2b4b32bdaec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287
    #2 0x402116 in _start (/home/kkleine/Development/asan-test/main-gcc-static+0x402116)
Address 0x7fff8f79d214 is located at offset 436 in frame <main> of T0's stack:
  This frame has 1 object(s):
    [32, 432) 'stack_array'
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /home/kkleine/Development/asan-test/main.cpp:5 main
Shadow bytes around the buggy address:
  0x100071eeb9f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba00: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
  0x100071eeba10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x100071eeba40: 00 00[f4]f4 f3 f3 f3 f3 00 00 00 00 00 00 00 00
  0x100071eeba50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x100071eeba90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:     fa
  Heap righ redzone:     fb
  Freed Heap region:     fd
  Stack left redzone:    f1
  Stack mid redzone:     f2
  Stack right redzone:   f3
  Stack partial redzone: f4
  Stack after return:    f5
  Stack use after scope: f8
  Global redzone:        f9
  Global init order:     f6
  Poisoned by user:      f7
  ASan internal:         fe
==25464== ABORTING
make: *** [using-gcc-static] Error 1

what_each_binary_links_against

$ ldd main-*
main-clang:
	linux-vdso.so.1 =>  (0x00007fff2a1fe000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ff4eb80a000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007ff4eb602000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007ff4eb2fb000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff4eb0f7000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007ff4eaee1000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff4eab1a000)
	/lib64/ld-linux-x86-64.so.2 (0x00007ff4eba63000)
main-gcc:
	linux-vdso.so.1 =>  (0x00007fffe6bae000)
	libasan.so.0 => /usr/lib/x86_64-linux-gnu/libasan.so.0 (0x00007f8b44a0e000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8b44648000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8b44429000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8b44225000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f8b479d8000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8b4400f000)
main-gcc-static:
	linux-vdso.so.1 =>  (0x00007fffd615b000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f29984f3000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f29982d5000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f29980be000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2997cf8000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f2998732000)

Any example of separate compilation and linking?

this is awesome -- thanks!

Extremely useful!

There is some example of separate compilation and linking: http://tsdgeos.blogspot.ru/2014/03/asan-and-libraries.html

The recommended way for GCC is to statically link against ASAN using -static-libasan.

Not really, -static-libasan gets second class support in GCC (see e.g. #64234 which has been opened for 4 years now) and also does not support separate sanitization of shared libraries.

The recommended way for GCC is to statically link against ASAN using -static-libasan.

Not really, -static-libasan gets second class support in GCC (see e.g. #64234 which has been opened for 4 years now) and also does not support separate sanitization of shared libraries.

@yugr thanks. I didn't know it back then.

always use -fsanitize=address https://groups.google.com/g/address-sanitizer/c/SD590XDinfQ/m/NMUPj_G0BgAJ?pli=1 (you are using a internal flags)