Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library

[Andrew Morton]

On Thu, 5 Jul 2018 08:44:18 -0700 Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> On Thu, Jul 5, 2018 at 7:55 AM,  <osalvador@xxxxxxxxxxxxxxxxxx> wrote:
> > From: Oscar Salvador <osalvador@xxxxxxx>
> >
> > The current code does not make sure to page align bss before calling
> > vm_brk(), and this can lead to a VM_BUG_ON() in __mm_populate()
> > due to the requested lenght not being correctly aligned.
> >
> > Let us make sure to align it properly.
> >
> > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> > Tested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> > Reported-by: syzbot+5dcb560fe12aa5091c06@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> Wow. CONFIG_USELIB? I'm surprised distros are still using this. 32-bit
> only, and libc5 and earlier only.

Presumably doesn't happen much, but people who *are* enabling this will
want the fix, so I added the cc:stable.