Sometimes wlan related TEXT causes segment fault, and backtrace shows it's strtok in iw_get_stats.
I read the code of wireless_tools, which says 'strtok not thread safe, not used in WE-12 and later' for iw_get_stats. But it need to first check if has_range and then we_version_compiled.
In conky/src/linux.cc, iw_get_stats is called before iw_get_range_info, hence has_range is always 0 in iw_get_stats and strtok is used. I simply move iw_get_range_info before iw_get_stats and no segfault up to now.