From: David Hildenbrand <redacted>
[ Upstream commit b159f94c86b43cf7e73e654bc527255b1f4eafc4 ]
... otherwise we will try unlocking a spinlock that was never locked via a
garbage pointer.
At the time we reach this code path, we usually successfully looked up
a PGSTE already; however, evil user space could have manipulated the VMA
layout in the meantime and triggered removal of the page table.
Fixes: 1e133ab296f3 ("s390/mm: split arch/s390/mm/pgtable.c")
Signed-off-by: David Hildenbrand <redacted>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20210909162248.14969-3-david@redhat.com (local)
Signed-off-by: Christian Borntraeger <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/mm/gmap.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -662,9 +662,10 @@ void __gmap_zap(struct gmap *gmap, unsig
vmaddr |= gaddr & ~PMD_MASK;
/* Get pointer to the page table entry */
ptep = get_locked_pte(gmap->mm, vmaddr, &ptl);
- if (likely(ptep))
+ if (likely(ptep)) {
ptep_zap_unused(gmap->mm, vmaddr, ptep, 0);
- pte_unmap_unlock(ptep, ptl);
+ pte_unmap_unlock(ptep, ptl);
+ }
}
}
EXPORT_SYMBOL_GPL(__gmap_zap);