Messages in this thread | | | From | Andy Lutomirski <> | Date | Wed, 14 May 2014 15:51:59 -0700 | Subject | Re: mm: NULL ptr deref handling mmaping of special mappings |
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On Wed, May 14, 2014 at 2:31 PM, Andrew Morton <akpm@linux-foundation.org> wrote: > 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?
You're almost right, but that was enough to point me in the right direction :)
The mapping is still needed, since there are two pages. qemu -no-hpet will trigger this, but the nohpet kernel option will not. The latter is arguably a bug in the nohpet option.
Fix coming.
-- Andy Lutomirski AMA Capital Management, LLC
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