Park, Geon (re-st)

목차

  1. AFL
  2. AFL++
  3. 입힌 뒤 확인

AFL - Makefile의 CFLAGS를 수정한다.

Makefile의 CFLAGS부분에 -fsanitize=address을 추가한다.

1CFLAGS     += -fsanitize=address -Wall -D_FORTIFY_SOURCE=2 -g -Wno-pointer-sign \
2
3        -DAFL_PATH=\"$(HELPER_PATH)\" -DDOC_PATH=\"$(DOC_PATH)\" \
4
5        -DBIN_PATH=\"$(BIN_PATH)\"

실패담

export AFL_USE_ASAN=1 은 왜인지 먹지 않는다.

AFL++ - ASAN_BUILD 환경변수를 설정한다.

1cd ./AFLplusplus && ASAN_BUILD="1" make clean all

ASAN crashlog에 줄 번호가 나오지 않을 것이다. addr2line을 쓰자.

ASAN crashlog에 나온 포인터를 addr2line으로 확인한다.

e.g. 로그가 아래와 같다면,

    #0 0x55c8f033ceb2  (/fuzzer/(...생략...)/afl-fuzz+0xe1eb2)
    #1 0x55c8f0348338  (/fuzzer/(...생략...)/afl-fuzz+0xed338)
    #2 0x55c8f02cad71  (/fuzzer/(...생략...)/afl-fuzz+0x6fd71)
    #3 0x55c8f02e2554  (/fuzzer/(...생략...)/afl-fuzz+0x87554)
    #4 0x55c8f03190cd  (/fuzzer/(...생략...)/afl-fuzz+0xbe0cd)
    #5 0x7fb81b3e6082  (/lib/x86_64-linux-gnu/libc.so.6+0x24082)
    #6 0x55c8f02858ed  (/fuzzer/(...생략...)/afl-fuzz+0x2a8ed)

AddressSanitizer can not provide additional info.

다음과 같이 확인한다.

addr2line -e /fuzzer/(...생략...)/afl-fuzz 0xe1eb2 0xed338 0x6fd71 0x87554 0xbe0cd 0x2a8ed
/fuzzer/(...생략...)/src/afl-fuzz-bitmap.c:779
/fuzzer/(...생략...)/src/afl-fuzz-run.c:1341
/fuzzer/(...생략...)/src/afl-fuzz-one.c:3536 (discriminator 1)
/fuzzer/(...생략...)/src/afl-fuzz-one.c:6722 (discriminator 1)
/fuzzer/(...생략...)/src/afl-fuzz.c:3814
??:?

실패담

1export ASAN_OPTIONS=abort_on_error=1,symbolize=1
2export ASAN_SYMBOLIZER_PATH=$(which llvm-symbolizer)
3vi GNUmakefile
4- [ ] # ifdef ASAN_BUILD 가서 -g 추가하기

instrumentation이 잘 되었는지 nm으로 사후 점검하자.

nm ./afl-fuzz | grep asan

#How-To