Messages in this thread | | | Date | Thu, 10 Jan 2019 00:52:32 -0500 (EST) | From | Pankaj Gupta <> | Subject | Re: [PATCH] mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one |
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> The conversion to use a structure for mmu_notifier_invalidate_range_*() > unintentionally changed the usage in try_to_unmap_one() to init the > 'struct mmu_notifier_range' with vma->vm_start instead of @address, > i.e. it invalidates the wrong address range. Revert to the correct > address range. > > Manifests as KVM use-after-free WARNINGs and subsequent "BUG: Bad page > state in process X" errors when reclaiming from a KVM guest due to KVM > removing the wrong pages from its own mappings. > > Reported-by: leozinho29_eu@hotmail.com > Reported-by: Mike Galbraith <efault@gmx.de> > Reported-by: Adam Borowski <kilobyte@angband.pl> > Cc: Jérôme Glisse <jglisse@redhat.com> > Cc: Christian König <christian.koenig@amd.com> > Cc: Jan Kara <jack@suse.cz> > Cc: Matthew Wilcox <mawilcox@microsoft.com> > Cc: Ross Zwisler <zwisler@kernel.org> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Felix Kuehling <felix.kuehling@amd.com> > Cc: Ralph Campbell <rcampbell@nvidia.com> > Cc: John Hubbard <jhubbard@nvidia.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for > invalidate_range_start/end calls v2") > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > > FWIW, I looked through all other calls to mmu_notifier_range_init() in > the patch and didn't spot any other unintentional functional changes. > > mm/rmap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 68a1a5b869a5..0454ecc29537 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1371,8 +1371,8 @@ static bool try_to_unmap_one(struct page *page, struct > vm_area_struct *vma, > * Note that the page can not be free in this function as call of > * try_to_unmap() must hold a reference on the page. > */ > - mmu_notifier_range_init(&range, vma->vm_mm, vma->vm_start, > - min(vma->vm_end, vma->vm_start + > + mmu_notifier_range_init(&range, vma->vm_mm, address, > + min(vma->vm_end, address + > (PAGE_SIZE << compound_order(page)))); > if (PageHuge(page)) { > /* > --
I was suspecting this patch for some other issue. But could not spot this after in depth analyzing the changed "invalidate_range_start/end calls".
Its indeed a good catch.
Reviewed-by: Pankaj gupta <pagupta@redhat.com>
> 2.19.2 > >
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