Sanitizers are a suite of open source tools from Google; like other memory debug tools, they tackle the usual common memory bugs and UB issues, including OOB (out-of-bounds accesses: read/write under/over-flow), UAF, UAR, double free, and memory leakage. One of the tools also handles data races in C/C++ code.
A key difference is that the sanitizer tools introduce instrumentation into the code via the compiler. They use a technology called Compile-time instrumentation (CTI) as well as shadow memory techniques. As of this writing, ASan is a part of and supports GCC ver 4.8 and LLVM (Clang) ver. 3.1 and above.
