Unaligned data access as found in USB (OTGv1) low-level driver for Cortex-M4 when complied with RVCT (Keil uVision MDK v5). Possible with other compilers too.
Complete information with suggested solution and patch see at forum topic: http://forum.chibios.org/phpbb/viewtopic.php?f=16&t=1468
Such unaligned accesses may probably exists in other drivers and/or core code.
Ideal solution (in my opinion) is correctly and explicitly enable HW unaligned access for Cortex-M3/M4. (May require code revision for those architectures which don't support unaligned support in HW).