In chibios/os/hal/ports/STM32/STM32L1xx/stm32_isr.h the USB LP vector for STM32L1xx is wrong:
Correct is:
This causes crash when trying to use USB.
(Reference: http://www.st.com/st-web-ui/static/active/en/resource/technical/document/reference_manual/CD00240193.pdf page 233)
Fixed in repository, will be released in 3.0.0p4.