Re: [PATCH] kasan: fix the missing underflow in memmove and memcpy with CONFIG_KASAN_GENERIC=y

[Walter Wu]

On Tue, 2019-10-08 at 05:47 -0400, Qian Cai wrote:
> 
> > On Oct 8, 2019, at 2:16 AM, Walter Wu <walter-zh...@mediatek.com> wrote:
> > 
> > It is an undefined behavior to pass a negative numbers to
> >    memset()/memcpy()/memmove(), so need to be detected by KASAN.
> 
> Why can’t this be detected by UBSAN?

I don't know very well in UBSAN, but I try to build ubsan kernel and
test a negative number in memset and kmalloc_memmove_invalid_size(), it
look like no check.