[Commotion-dev] Can't talk between desktop OLSRd and Commotion OpenWRT boxes

[Hans-Christoph Steiner]

This is a super useful report!  Thanks for taking the time to do this.  Sounds
like something that we should take up on the olsr-dev list, since it affects
olsr directly.  Do you want to post this there?  Otherwise I'm happy to do it.

.hc

On 03/09/2013 01:34 PM, Mikael Nordfeldth wrote:
> 2013-03-08 19:27, Hans-Christoph Steiner skrev:
>> That would be quite useful if you have the time!  Another thing that might the
>> whole process easier is to 'git bisect', if you are familiar with that..
>> Right now, Debian squeeze and wheezy have 0.6.2, and Ubuntu has 0.6.1 and 0.6.3:
>>
>> http://packages.debian.org/search?keywords=olsrd
>> http://packages.ubuntu.com/search?keywords=olsrd
>>
>> So the idea is to find out which version of these we can rely on, and which we
>> need to use replacements.
> 
> Gah. This seems way more advanced than what I can explain with my
> knowledge. Nevertheless, I did find what caused my error, the -O2 gcc
> optimization switch as patched by Debian package "hardening fixes":
> 
> 1. I tried compiling various olsrd versions. All worked.
> 2. I tried compiling 0.6.3-5~quantal from 'apt-get source'. It didn't work.
> 3. I tried compiling the 0.6.3.orig source (same as above, without
> debian patches) It worked.
> 4. None of the patches contained any networking code (except the json
> plugin, but disabling it didn't have any effect anyway)
> 5. I found that removing the -O2 switch on line 227 in Makefile.inc, as
> patched by 310-hardening-fixes.patch resolved my invalid argument
> sendto(v4) issue:
> 
>  %.o: %.c
>         @echo "[CC] $<"
> -       $(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
> +       $(CC) -O2 $(CFLAGS) $(CPPFLAGS) -fPIE -c -o $@ $<
> 
> 
> Reverting this (and even leaving the -fPIE there but removing -O2) makes
> the resulting binary functional.
> 
> 
> So the specific problem was caused by the -O2 parameter to gcc, I guess
> making it a compiling/linking issue. I don't know enough about this
> myself though, so I'm attaching ('O2-opts') the output of what that
> level of optimizations means if anyone is interested (gcc -c -Q -O2
> --help=optimizers)
> 
> More info on my build environment is below:
> 
> $ gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
> Target: x86_64-linux-gnu
> Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
> 4.7.2-2ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
> --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
> --program-suffix=-4.7 --enable-shared --enable-linker-build-id
> --with-system-zlib --libexecdir=/usr/lib --without-included-gettext
> --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
> --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
> --enable-libstdcxx-debug --enable-libstdcxx-time=yes
> --enable-gnu-unique-object --enable-plugin --enable-objc-gc
> --disable-werror --with-arch-32=i686 --with-tune=generic
> --enable-checking=release --build=x86_64-linux-gnu
> --host=x86_64-linux-gnu --target=x86_64-linux-gnu
> Thread model: posix
> gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1)
> 
> 
> $ uname -a
> Linux plexi 3.5.0-25-generic #39-Ubuntu SMP Mon Feb 25 18:26:58 UTC 2013
> x86_64 x86_64 x86_64 GNU/Linux
>