This is a note to let you know that I've just added the patch titled s390/gmap: don't unconditionally call pte_unmap_unlock() in __gmap_zap() to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-gmap-don-t-unconditionally-call-pte_unmap_unloc.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 1ed2fc384482fde0e026bfd94a4259f91ea9e5c1 Author: David Hildenbrand <david@xxxxxxxxxx> Date: Thu Sep 9 18:22:41 2021 +0200 s390/gmap: don't unconditionally call pte_unmap_unlock() in __gmap_zap() [ 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 <david@xxxxxxxxxx> Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210909162248.14969-3-david@xxxxxxxxxx Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 7cde0f2f52e14..65ccb9d797270 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -684,9 +684,10 @@ void __gmap_zap(struct gmap *gmap, unsigned long gaddr) 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);