va_end() must be called from the same function that calls va_start(). This is not done for sprintf() and other functions.
We found issues with mspgcc 4.7.0 that may be related to sprintf.
Could you add a simple example to trigger this bug here?
Peter A. Bigot
Actually, I can't; the issue was discovered by inspection within embtextf, not by encountering an actual problem. I don't have a patch prepared for msp430-libc yet, but the solution will be similar to the approach taken in https://github.com/pabigot/embtextf/blob/master/src/libc.c if you'd like to try that locally to see if it fixes the problem.