Some of what ubsan does sounds like the featureset of Valgrind; e.g. detecting uninitialised variables and accesses outside of allocated memory, except it can catch a few more bugs.

The fact that undefined behaviour is in practice a real pain has prompted some work on C variants which replace most instances of UB with more reasonable implementation-defined behaviour instead, e.g. http://blog.regehr.org/archives/1180 (discussed before here: https://news.ycombinator.com/item?id=8233484 )