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s390/uv: fully validate the VMA before calling follow_page()

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[ Upstream commit 46c22ffd27 ]

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 dd2283f260 ("mm: mmap: zap pages
with read mmap_sem in munmap").

find_vma() does not check if the address is >= the VMA start address;
use vma_lookup() instead.

Fixes: 214d9bbcd3 ("s390/mm: provide memory management functions for protected KVM guests")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/r/20210909162248.14969-6-david@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Hildenbrand 2021-09-09 18:22:44 +02:00 committed by Greg Kroah-Hartman
parent a9c017ab05
commit eadbd5d1ec
1 changed files with 1 additions and 1 deletions
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2
arch/s390/kernel/uv.c
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@ -212,7 +212,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
uaddr = __gmap_translate(gmap, gaddr);
if (IS_ERR_VALUE(uaddr))
goto out;
vma = find_vma(gmap->mm, uaddr);
vma = vma_lookup(gmap->mm, uaddr);
if (!vma)
goto out;
/*