Repository navigation
memrchr uses unaligned loads #35967
Description
Activity
This was suspected to cause a crash using ARMv7, found by @tomaka
The crash is a SIGBUS (which is usually caused by unaligned loads), so this is likely the cause.
If anyone want to find more, the exact location is
_ZN3std6memchr7memrchr17hbaa18487c977cd24E+164, using the rustc nightly from 2016-08-18. I don't know how to introspect the debug infos to find what exactly is the instruction at this location. EDIT: Oh, since libstd is compiled in release there's probably no debug info anyway.The crash disappeared after the latest nightly.
Thank you
Due to an arithmetic error, the fallback memrchr (used for non-linux) in libstd uses unaligned loads, the intention was to produce only well aligned pointers of course.
This was suspected to cause a crash using ARMv7, found by @tomaka
Original code also had the same issue: BurntSushi/memchr/pull/9
I believe that on x86 non-linux platforms, the bug was harmless and the function still produced the correct return value.