Control: retitle -1 afl: FTBFS on armhf (illegal instruction in afl-clang-fast)

On Fri, 21 Oct 2016 02:08:28 +0200 Daniel Stender wrote:

> Thanks for any input (if this could be worked around in the AFL package),

I am able to reproduce the failure on abel but not harris/asachi.

Retitling the bug since it occurs in afl-clang-fast not in the test code:

Program received signal SIGILL, Illegal instruction.
0x7f556094 in edit_params (argc=<optimized out>, argv=<optimized out>) at 
afl-clang-fast.c:224
224       cc_params[cc_par_cnt++] = "-D__AFL_HAVE_MANUAL_CONTROL=1";

These are the CPU features for each of them:

abel:   Features : swp half thumb fastmult vfp edsp thumbee      vfpv3 tls      
 idiva idivt vfpd32 lpae 
asachi: Features :     half thumb fastmult vfp edsp         neon vfpv3 tls 
vfpv4 idiva idivt        lpae evtstrm
harris: Features : swp half thumb fastmult vfp edsp thumbee neon vfpv3 tls      
             vfpd32 

Seems like the issue is lack of neon since that is the only thing in
common between harris/asachi that is missing on abel.

I disassembled the code where the crash happens & got this instruction:

=> 0x7f556094 <+1924>:  vst1.32 {d16-d17}, [r0]!

Doing a web search indicates this is a NEON instruction. The binary
(afl-clang-fast) that contains vst1.32 was compiled by clang-3.9.
Looking at build logs, the failures started when afl started building
with LLVM 3.8.

-- 
bye,
pabs

https://wiki.debian.org/PaulWise

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