Arm + KASAN + syzbot

[Linus Walleij]

On Thu, Mar 11, 2021 at 3:55 PM Arnd Bergmann <arnd at arndb.de> wrote:

> If KASAN limits the address space available to user space, there might be
> a related issue, even when there is still physical memory available.

So in this case with the 2/2 split userspace TASK_SIZE
will be (include/asm/memory.h) KASAN_SHADOW_START
which in this case is 0x6ee00000.
Details in
commit c12366ba441da2f6f2b915410aca2b5b39c1651,

I'm just puzzled that OOM is not kicking in if the binary
runs out of virtual memory (hits 0x6ee00000).
It sure occurse when we run out of physical memory,
that has happened to me on 16MB systems.

What happens if we just use PAGE_OFFSET 0xC0000000
like most platforms? This free:s up a whole bunch of virtual
memory for userspace (will be 0xb6e00000).

Yours,
Linus Walleij