Messages in this thread | | | Date | Sun, 28 Nov 2021 12:54:40 +0100 | From | Greg KH <> | Subject | Re: [PATCH for 4.14-stable] s390/mm: validate VMA in PGSTE manipulation functions |
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On Fri, Nov 26, 2021 at 06:15:36PM +0100, David Hildenbrand wrote: > commit fe3d10024073f06f04c74b9674bd71ccc1d787cf upstream. > > We should not walk/touch page tables outside of VMA boundaries when > holding only the mmap sem in read mode. Evil user space can modify the > VMA layout just before this function runs and e.g., trigger races with > page table removal code since commit dd2283f2605e ("mm: mmap: zap pages > with read mmap_sem in munmap"). gfn_to_hva() will only translate using > KVM memory regions, but won't validate the VMA. > > Further, we should not allocate page tables outside of VMA boundaries: if > evil user space decides to map hugetlbfs to these ranges, bad things will > happen because we suddenly have PTE or PMD page tables where we > shouldn't have them. > > Similarly, we have to check if we suddenly find a hugetlbfs VMA, before > calling get_locked_pte(). > > Fixes: 2d42f9477320 ("s390/kvm: Add PGSTE manipulation functions") > Signed-off-by: David Hildenbrand <david@redhat.com> > Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > Acked-by: Heiko Carstens <hca@linux.ibm.com> > Link: https://lore.kernel.org/r/20210909162248.14969-4-david@redhat.com > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > arch/s390/mm/pgtable.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+)
What about for 5.10-stable and 5.4-stable and 4.19-stable? Will this commit work there as well?
thanks,
greg k-h
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