Re: mm: NULL ptr deref handling mmaping of special mappings

Andrew Morton
2014-05-14T21:31:27Z

On Wed, 14 May 2014 17:11:00 -0400 Sasha Levin <sasha.levin@oracle.com> wrote:

> > In my linux-next all that code got deleted by Andy's "x86, vdso:
> > Reimplement vdso.so preparation in build-time C" anyway. What kernel
> > were you looking at?
>
> Deleted? It appears in today's -next. arch/x86/vdso/vma.c:124 .
>
> I don't see Andy's patch removing that code either.

ah, OK, it got moved from arch/x86/vdso/vdso32-setup.c into
arch/x86/vdso/vma.c.

Maybe you managed to take a fault against the symbol area between the
_install_special_mapping() and the remap_pfn_range() call, but mmap_sem
should prevent that.

Or the remap_pfn_range() call never happened. Should map_vdso() be
running _install_special_mapping() at all if
image->sym_vvar_page==NULL?