> So the fortify_string code has decided that only a single-byte (or
> empty) memcpy is ok.
>
> And that, in turn, seems to be because we're copying from
> optprobe_template_entry, which is declared as
>
> extern __visible kprobe_opcode_t optprobe_template_entry;
>
> so the fortify code decides it's a single character.
>
> Does just changing all those things to be declared as arrays fix
> things?
Yeah, that fixes it because GCC will consider the size of 'char foo[]'
unknown (i.e. (size_t)-1 from __builtin_object_size).
GCC doesn't know this essentially constant value at compile-time so it
wasn't a compile-time error:
#define TMPL_END_IDX \
((long)&optprobe_template_end - (long)&optprobe_template_entry)
-fsanitize=object-size works the same way for pointer dereferences so
replacing might fix some issues for CONFIG_UBSAN_SANITIZE_ALL. I guess
that's way too noisy at the moment thus the !COMPILE_TEST.
