Subject: Re: Arm + KASAN + syzbot

From: Russell King - ARM Linux admin <[email-masked]>
Date: Mon, 15 Mar 2021 19:03:11 +0000

On Mon, Mar 15, 2021 at 03:01:32PM +0100, Linus Walleij wrote:
> On Thu, Mar 11, 2021 at 3:55 PM Arnd Bergmann <[email-masked]> 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.
> 
> I'm just puzzled that OOM is not kicking in if the binary
> runs out of virtual memory (hits 0x6ee00000).

The OOM-killer has nothing to do with the virtual space for processes.
The OOM-killer is about physical page starvation in the kernel.

A process will instead find mmap() returning NULL or attempts to
increase the heap via brk() failing.

Neither of these events should result in any effect on the kernel;
the process on the other hand may make an illegal access and be
given a segfault.

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