On Tue, May 30, 2023 at 10:39 AM Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > lib/string.c is built with -ffreestanding, which prevents the compiler > from replacing certain functions with calls to their library versions. > > On the other hand, this also prevents Clang and GCC from instrumenting > calls to memcpy() when building with KASAN, KCSAN or KMSAN: > - KASAN normally replaces memcpy() with __asan_memcpy() with the > additional cc-param,asan-kernel-mem-intrinsic-prefix=1; > - KCSAN and KMSAN replace memcpy() with __tsan_memcpy() and > __msan_memcpy() by default. > > To let the tools catch memory accesses from strlcpy/strlcat, replace > the calls to memcpy() with __builtin_memcpy(), which KASAN, KCSAN and > KMSAN are able to replace even in -ffreestanding mode. > > This preserves the behavior in normal builds (__builtin_memcpy() ends up > being replaced with memcpy()), and does not introduce new instrumentation > in unwanted places, as strlcpy/strlcat are already instrumented. > > Suggested-by: Marco Elver <elver@xxxxxxxxxx> > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@xxxxxxxxxx/ Sorry, missed a "Reviewed-by: Marco Elver <elver@xxxxxxxxxx>" from the previous thread: https://lore.kernel.org/lkml/CAG_fn=UzQ-jnQrxzvLE6EV37zSVCOGPmsVTxyfp1wXzBir4vAg@xxxxxxxxxxxxxx/T/ > Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
