[llvm-dev] ASAN not finding any bugs? (original) (raw)

Tobias Hieta via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 3 11:47:15 PST 2020

After experimenting a bit with godbolt it seems like asan is removed from the codegen when the new pass manager is used: https://godbolt.org/z/ccrMiN

But this also seems fixed if you switch to clang 9.0.0.

On Mon, Feb 3, 2020 at 8:38 PM Tobias Hieta <tobias at plexapp.com> wrote:

Hello Alex, Thanks for the hint. It was actually not the -O flag that created the problem. But it pointed me in the right direction, when I passed -fno-experimental-new-pass-manager it started to show the error. My guess is that the new pass manager is more aggressive in removing UB? Thanks, Tobias On Mon, Feb 3, 2020 at 5:29 PM Alex Brachet-Mialot <alexbrachetmialot at gmail.com> wrote: > > I haven’t looked at the code gen yet because I’m not on my computer right now but I suspect that at -Os the compiler is optimizing this away because it knows it to be undefined behavior. Try with -O0. > > On Mon, Feb 3, 2020 at 10:53 AM Tobias Hieta via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> Hello, >> >> I am building sanitizers for our different platforms and trying to use >> it in an example program, but while it seems like ASAN is running it's >> init functions (see stdout below with ASANOPTIONS=verbosity=1) it >> never catches anything in the program. This is LLVM 8.0.1 btw. >> >> I was using this small test case: >> >> int main(int argc, char** argv) { >> int *array = new int[100]; >> delete [] array; >> return array[argc]; // BOOM >> } >> >> I am compiling with: >> >> >> clang++ -resource-dir -fsanitize=address >> -shared-libasan -fno-omit-frame-pointer -Os -g -Wl,-rpath,> sanitizers> -o hello hello.cpp >> >> This is the output from setting verbosity=1 - how can I debug this issue? >> >> ==3401806==AddressSanitizer: libc interceptors initialized >> || [0x10007fff8000, 0x7fffffffffff] || HighMem || >> || [0x02008fff7000, 0x10007fff7fff] || HighShadow || >> || [0x00008fff7000, 0x02008fff6fff] || ShadowGap || >> || [0x00007fff8000, 0x00008fff6fff] || LowShadow || >> || [0x000000000000, 0x00007fff7fff] || LowMem || >> MemToShadow(shadow): 0x00008fff7000 0x000091ff6dff 0x004091ff6e00 0x02008fff6fff >> redzone=16 >> maxredzone=2048 >> quarantinesizemb=256M >> threadlocalquarantinesizekb=1024K >> malloccontextsize=30 >> SHADOWSCALE: 3 >> SHADOWGRANULARITY: 8 >> SHADOWOFFSET: 0x7fff8000 >> ==3401806==Installed the sigaction for signal 11 >> ==3401806==Installed the sigaction for signal 7 >> ==3401806==Installed the sigaction for signal 8 >> ==3401806==T0: stack [0x7fff3bf5c000,0x7fff3c75c000) size 0x800000; >> local=0x7fff3c759244 >> ==3401806==AddressSanitizer Init done >> >> ➜ readelf -d hello >> >> Dynamic section at offset 0xe18 contains 25 entries: >> Tag Type Name/Value >> 0x0000000000000001 (NEEDED) Shared library: [libclangrt.asan-x8664.so] >> 0x0000000000000001 (NEEDED) Shared library: [libstdc++.so.6] >> 0x0000000000000001 (NEEDED) Shared library: [libm.so.6] >> 0x0000000000000001 (NEEDED) Shared library: [libgccs.so.1] >> 0x0000000000000001 (NEEDED) Shared library: [libc.so.6] >> 0x000000000000000c (INIT) 0x400570 >> 0x000000000000000d (FINI) 0x4007b8 >> 0x0000000000000004 (HASH) 0x400278 >> 0x0000000000000005 (STRTAB) 0x400318 >> 0x0000000000000006 (SYMTAB) 0x4002a0 >> 0x000000000000000a (STRSZ) 462 (bytes) >> 0x000000000000000b (SYMENT) 24 (bytes) >> 0x0000000000000015 (DEBUG) 0x0 >> 0x0000000000000003 (PLTGOT) 0x601000 >> 0x0000000000000002 (PLTRELSZ) 72 (bytes) >> 0x0000000000000014 (PLTREL) RELA >> 0x0000000000000017 (JMPREL) 0x400528 >> 0x0000000000000007 (RELA) 0x400510 >> 0x0000000000000008 (RELASZ) 24 (bytes) >> 0x0000000000000009 (RELAENT) 24 (bytes) >> 0x000000006ffffffe (VERNEED) 0x4004f0 >> 0x000000006fffffff (VERNEEDNUM) 1 >> 0x000000006ffffff0 (VERSYM) 0x4004e6 >> 0x0000000000000000 (NULL) 0x0 _>> ________________________ >> LLVM Developers mailing list >> llvm-dev at lists.llvm.org >> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

More information about the llvm-dev mailing list