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authorDavid Hildenbrand <david@redhat.com>2021-09-09 19:22:41 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-11-26 13:40:31 +0300
commitccf592fbe493200df9d931c1c2bc73b9701c1064 (patch)
tree382a8a406cb2c4b6cf851bfeb31c12639f5d8916 /arch/s390/mm/gmap.c
parentaa88387bb8b082de70973ee6b40ee71322b97e34 (diff)
downloadlinux-ccf592fbe493200df9d931c1c2bc73b9701c1064.tar.xz
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@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Link: https://lore.kernel.org/r/20210909162248.14969-3-david@redhat.com Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/s390/mm/gmap.c')
-rw-r--r--arch/s390/mm/gmap.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index a29d2e88b00e..fb121440b1c8 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -665,9 +665,10 @@ 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);