On 11/12/19 9:53 AM, Walter Wu wrote: > KASAN missed detecting size is a negative number in memset(), memcpy(), > and memmove(), it will cause out-of-bounds bug. So needs to be detected > by KASAN. > > If size is a negative number, then it has a reason to be defined as > out-of-bounds bug type. > Casting negative numbers to size_t would indeed turn up as > a large size_t and its value will be larger than ULONG_MAX/2, > so that this can qualify as out-of-bounds. > > KASAN report is shown below: > > BUG: KASAN: out-of-bounds in kmalloc_memmove_invalid_size+0x70/0xa0 > Read of size 18446744073709551608 at addr ffffff8069660904 by task cat/72 > > CPU: 2 PID: 72 Comm: cat Not tainted 5.4.0-rc1-next-20191004ajb-00001-gdb8af2f372b2-dirty #1 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace+0x0/0x288 > show_stack+0x14/0x20 > dump_stack+0x10c/0x164 > print_address_description.isra.9+0x68/0x378 > __kasan_report+0x164/0x1a0 > kasan_report+0xc/0x18 > check_memory_region+0x174/0x1d0 > memmove+0x34/0x88 > kmalloc_memmove_invalid_size+0x70/0xa0 > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=199341 > > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Cc: Alexander Potapenko <glider@xxxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > --- Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
