[llvm-dev] Some feedback on Libfuzzer

[Greg Stark via llvm-dev]

On Sat, Sep 12, 2015 at 7:48 PM, Greg Stark <stark at mit.edu> wrote:
> I get that even if I put -fPIE in CFLAGS.

Er, yeah. Even a trivial test case doesn't work:

$ cat foo.c
int main(int argc, char *argv[], char *envp[]) {
return 1;
}

$ clang -o foo -fsanitize=memory -fPIE -pie   foo.c

$ sysctl kernel.randomize_va_space
kernel.randomize_va_space = 2

$ ./foo
FATAL: Code 0x55873d194390 is out of application range. Non-PIE build?
FATAL: MemorySanitizer can not mmap the shadow memory.
FATAL: Make sure to compile with -fPIE and to link with -pie.
FATAL: Disabling ASLR is known to cause this error.
FATAL: If running under GDB, try 'set disable-randomization off'.
==25950==Process memory map follows:
0x55873d177000-0x55873d216000 /tmp/foo
0x55873d415000-0x55873d419000 /tmp/foo
0x55873d419000-0x55873f88c000
0x7f276d5cf000-0x7f276d921000
0x7f276d921000-0x7f276dac0000 /lib/x86_64-linux-gnu/libc-2.19.so
0x7f276dac0000-0x7f276dcc0000 /lib/x86_64-linux-gnu/libc-2.19.so
0x7f276dcc0000-0x7f276dcc4000 /lib/x86_64-linux-gnu/libc-2.19.so
0x7f276dcc4000-0x7f276dcc6000 /lib/x86_64-linux-gnu/libc-2.19.so
0x7f276dcc6000-0x7f276dcca000
0x7f276dcca000-0x7f276dce0000 /lib/x86_64-linux-gnu/libgcc_s.so.1
0x7f276dce0000-0x7f276dedf000 /lib/x86_64-linux-gnu/libgcc_s.so.1
0x7f276dedf000-0x7f276dee0000 /lib/x86_64-linux-gnu/libgcc_s.so.1
0x7f276dee0000-0x7f276dee3000 /lib/x86_64-linux-gnu/libdl-2.19.so
0x7f276dee3000-0x7f276e0e2000 /lib/x86_64-linux-gnu/libdl-2.19.so
0x7f276e0e2000-0x7f276e0e3000 /lib/x86_64-linux-gnu/libdl-2.19.so
0x7f276e0e3000-0x7f276e0e4000 /lib/x86_64-linux-gnu/libdl-2.19.so
0x7f276e0e4000-0x7f276e1e4000 /lib/x86_64-linux-gnu/libm-2.19.so
0x7f276e1e4000-0x7f276e3e3000 /lib/x86_64-linux-gnu/libm-2.19.so
0x7f276e3e3000-0x7f276e3e4000 /lib/x86_64-linux-gnu/libm-2.19.so
0x7f276e3e4000-0x7f276e3e5000 /lib/x86_64-linux-gnu/libm-2.19.so
0x7f276e3e5000-0x7f276e3ec000 /lib/x86_64-linux-gnu/librt-2.19.so
0x7f276e3ec000-0x7f276e5eb000 /lib/x86_64-linux-gnu/librt-2.19.so
0x7f276e5eb000-0x7f276e5ec000 /lib/x86_64-linux-gnu/librt-2.19.so
0x7f276e5ec000-0x7f276e5ed000 /lib/x86_64-linux-gnu/librt-2.19.so
0x7f276e5ed000-0x7f276e605000 /lib/x86_64-linux-gnu/libpthread-2.19.so
0x7f276e605000-0x7f276e804000 /lib/x86_64-linux-gnu/libpthread-2.19.so
0x7f276e804000-0x7f276e805000 /lib/x86_64-linux-gnu/libpthread-2.19.so
0x7f276e805000-0x7f276e806000 /lib/x86_64-linux-gnu/libpthread-2.19.so
0x7f276e806000-0x7f276e80a000
0x7f276e80a000-0x7f276e82a000 /lib/x86_64-linux-gnu/ld-2.19.so
0x7f276ea03000-0x7f276ea08000
0x7f276ea1e000-0x7f276ea2a000
0x7f276ea2a000-0x7f276ea2b000 /lib/x86_64-linux-gnu/ld-2.19.so
0x7f276ea2b000-0x7f276ea2c000 /lib/x86_64-linux-gnu/ld-2.19.so
0x7f276ea2c000-0x7f276ea2d000
0x7ffd99d31000-0x7ffd99d52000 [stack]
0x7ffd99d73000-0x7ffd99d75000 [vvar]
0x7ffd99d75000-0x7ffd99d77000 [vdso]
0xffffffffff600000-0xffffffffff601000 [vsyscall]
==25950==End of process memory map.


-- 
greg