[cfe-dev] Undefined reference to dfsan_add_label in dataflow sanitizer

[Frederico Araujo]

Hi,

When  trying to use the function *dfsan_add_label* defined in the dataflow
sanitizer interface I get an undefined reference error. Other functions
such as *dfsan_create_label* and *dfsan_set_label* work fine. I can emulate
this function by using dfsan_union and fsan_set_label, but I'm curious to
understand why it's undefined. Any ideas?

Here is the output of compilation with -v flag:

clang version 3.5.0 (208131)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
 "/usr/local/llvm/cmakebuild/bin/clang-3.5" -cc1 -triple
x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free
-disable-llvm-verifier -main-file-name mrpoc.c -mrelocation-model pic
-pic-level 2 -pie-level 2 -mdisable-fp-elim -fmath-errno -masm-verbose
-mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64
-v -resource-dir /usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0
-internal-isystem /usr/local/include -internal-isystem
/usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0/include
-internal-externc-isystem /usr/include/x86_64-linux-gnu
-internal-externc-isystem /include -internal-externc-isystem /usr/include
-fdebug-compilation-dir /home/frederico/dev/tests/llvm/mr -ferror-limit 19
-fmessage-length 116 -fsanitize=dataflow
-fsanitize-blacklist=/usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0/dfsan_abilist.txt
-mstackrealign -fobjc-runtime=gcc -fdiagnostics-show-option
-fcolor-diagnostics -o /tmp/mrpoc-da2ec3.o -x c mrpoc.c
clang -cc1 version 3.5.0 based upon LLVM 3.5.0svn default target
x86_64-unknown-linux-gnu
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
 "/usr/bin/ld" -whole-archive
/usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0/lib/linux/libclang_rt.dfsan-x86_64.a
-no-whole-archive -pie -z relro --hash-style=gnu --build-id --eh-frame-hdr
-m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o mrpoc
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/Scrt1.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtbeginS.o
-L/usr/lib/gcc/x86_64-linux-gnu/4.8
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu
-L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../..
-L/usr/local/llvm/cmakebuild/bin/../lib -L/lib -L/usr/lib
/tmp/mrpoc-da2ec3.o -lpthread -lrt -lm -ldl
--dynamic-list=/usr/local/llvm/cmakebuild/bin/../lib/clang/3.5.0/lib/linux/libclang_rt.dfsan-x86_64.a.syms
-lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
--no-as-needed /usr/lib/gcc/x86_64-linux-gnu/4.8/crtendS.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
/tmp/mrpoc-da2ec3.o: In function `main':
mrpoc.c:(.text+0xb3): undefined reference to `dfsan_add_label'
/tmp/mrpoc-da2ec3.o: In function `dfsw$dfsan_add_label':
mrpoc.c:(.text.dfsw$dfsan_add_label[dfsw$dfsan_add_label]+0xb): undefined
reference to `dfsan_add_label'
clang-3.5: error: linker command failed with exit code 1

Thanks,
Fred
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