On Mon, May 18, 2020 at 5:09 PM Qian Cai <cai@xxxxxx> wrote:
On Mon, May 18, 2020 at 7:55 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
On Sun, May 17, 2020 at 7:45 PM Qian Cai <cai@xxxxxx> wrote:
With Clang 9.0.1,
return array->value + array->elem_size * (index & array->index_mask);
but array->value is,
char value[0] __aligned(8);
This, and ptrs and pptrs, should be flexible arrays. But they are in a
union, and unions don't support flexible arrays. Putting each of them
into anonymous struct field also doesn't work:
/data/users/andriin/linux/include/linux/bpf.h:820:18: error: flexible
array member in a struct with no named members
struct { void *ptrs[] __aligned(8); };
So it probably has to stay this way. Is there a way to silence UBSAN
for this particular case?
I am not aware of any way to disable a particular function in UBSAN
except for the whole file in kernel/bpf/Makefile,
UBSAN_SANITIZE_arraymap.o := n
If there is no better way to do it, I'll send a patch for it.
That's probably going to be too drastic, we still would want to
validate the rest of arraymap.c code, probably. Not sure, maybe
someone else has better ideas.