On Mon, Feb 13, 2023 at 12:01:40PM +0100, Jakub Jelinek wrote: > The current gcc behavior is that operations like aggregate copies, or > clearing which might or might not need memcpy/memset/memmove under the hood > later are asan instrumented before the operation (in order not to limit the > choices on how it will be expanded), uses of builtins (__builtin_ prefixed > or not) are also instrumented before the calls unless they are one of the > calls that is recognized as always instrumented. None for hwasan, > for asan: > index, memchr, memcmp, memcpy, memmove, memset, strcasecmp, strcat, strchr, > strcmp, strcpy, strdup, strlen, strncasecmp, strncat, strncmp, strcspn, > strpbrk, strspn, strstr, strncpy > and for those builtins gcc disables inline expansion and enforces a library > call (but until the expansion they are treated in optimizations like normal > builtins and so could be say DCEd, or their aliasing behavior is considered > etc.). kasan behaves the same I think. > > Now, I think libasan only has __asan_ prefixed > __asan_memmove, __asan_memset and __asan_memcpy, nothing else, so most of > the calls from the above list even can't be prefixed. > > So, do you want for --param asan-kernel-mem-intrinsic-prefix=1 to __asan_ > prefix just memcpy/memmove/memset and nothing else? Is it ok to emit > memcpy/memset/memmove from aggregate operations which are instrumented > already at the caller (and similarly is it ok to handle those operations > inline)? I'm thinking it is trivial to add more __asan prefixed functions as needed, while trying to untangle the trainwreck created by assuming the normal functions are instrumented is much more work.
