Building libav with aflgo

[irfanariq]

Hi,

I would like to fuzz avconv from libav with AFLGo. These are the commands I used to build libav:

export AFLGO=path/to/aflgo
export CC=$AFLGO/afl-clang-fast
export CXX=$AFLGO/afl-clang-fast
cd path/to/libav
mkdir temp; mkdir obj-aflgo
export TMP_DIR=$PWD/temp
export LDFLAGS=-lpthread
export ADDITIONAL="-targets=$TMP_DIR/BBtargets.txt -outdir=$TMP_DIR -flto -fuse-ld=gold -Wl,-plugin-opt=save-temps"
cd obj-aflgo
../configure --cc=$CC --prefix=`pwd` --extra-cflags="$ADDITIONAL" --disable-shared

However, I got a C compiler test failed error saying temp/test.o: file not recognized: File format not recognized. I guess that the test failed because afl-clang-fast generate the IR bitcode instead of the ELF object file. I have read #69 and #71, and they suggest using --host-cflags. So, I changed the configure command to:

../configure --cc=$CC --prefix=`pwd` --host-cflags="$ADDITIONAL" --disable-shared --disable-doc

Using the above configure command, configuring the makefile and building the libav can be done successfully but afl-clang-fast does not generate the dot-files. The BBnames.txt and BBcalls.txt are also empty. Therefore, I cannot calculate the distance.

Would you please help me to build libav with aflgo?

Here is the commit hash of the libav and the BBtargets.txt :

Commuit hash : c4642788e83b0858bca449f9b6e71ddb015dfa5d
BBtargets.txt:

libavcodec/aacdec.c:2578
libavcodec/aacdec.c:2631
libavcodec/aacdec.c:2666
libavcodec/aacdec.c:2944
libavcodec/aacdec.c:3010
libavcodec/decode.c:336
libavcodec/decode.c:387
libavcodec/decode.c:405
libavcodec/decode.c:466
libavformat/utils.c:1950
libavformat/utils.c:2459
avtools/avconv_opt.c:821
avtools/avconv_opt.c:2467
avtools/avconv_opt.c:2504
avtools/avconv.c:2953

Thank you.

[strongcourage]

Hi @irfanariq, currently I don't have AFLGo in my laptop, so I am not able to test it. Can you fuzz libav using the hash and the targets in #69?

[irfanariq]

Hi @strongcourage, thank you for your response. I have tried the hash and target in #69 but afl-clang-fast still does not generate the dot-files. BBcalls.txt, BBnames.txt, Fnames.txt, and Ftargets.txt are empty too. So, I still can not calculate the distance.

[vannussina]

Are there any new ideas on this issue? I'm experiencing the same both with ffmpeg and libav. Seems like the ADDITIONAL flag passed via --hostc-flags does not reach aflgo-clang and it skips its first run where it should create CFG and CG and solely executes distance instrumentation. I tried several configurations for configure but either no distance files were created or compilation failed.