Re: [PATCH 3.10 112/139] mm: fix overflow check in expand_upwards()

[Geert Uytterhoeven]

On Wed, Nov 1, 2017 at 10:26 PM, Willy Tarreau <w@xxxxxx> wrote:
> From: Helge Deller <deller@xxxxxx>
>
> commit 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf upstream.
>
> JÃÂrn Engel noticed that the expand_upwards() function might not return

JÃrn (yeah, the original commit suffers from this, too ;-)

> -ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
> if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.
>
> Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
> which all define TASK_SIZE as 0xffffffff, but since none of those have
> an upwards-growing stack we currently have no actual issue.
>
> Nevertheless let's fix this just in case any of the architectures with
> an upward-growing stack (currently parisc, metag and partly ia64) define
> TASK_SIZE similar.
>
> Link: http://lkml.kernel.org/r/20170702192452.GA11868@xxxxxxxx
> Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
> Signed-off-by: Helge Deller <deller@xxxxxx>
> Reported-by: JÃrn Engel <joern@xxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Willy Tarreau <w@xxxxxx>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds