6.18-stable review patch. If anyone has any objections, please let me know.
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From: Claudio Imbrenda imbrenda@linux.ibm.com
[ Upstream commit 2f393c228cc519ddf19b8c6c05bf15723241aa96 ]
A few checks were missing in gmap_helper_zap_one_page(), which can lead to memory corruption in the guest under specific circumstances.
Add the missing checks.
Fixes: 5deafa27d9ae ("KVM: s390: Fix to clear PTE when discarding a swapped page") Cc: stable@vger.kernel.org Reported-by: Marc Hartmayer mhartmay@linux.ibm.com Tested-by: Marc Hartmayer mhartmay@linux.ibm.com Acked-by: Christian Borntraeger borntraeger@linux.ibm.com Signed-off-by: Claudio Imbrenda imbrenda@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com [ adapted ptep_zap_softleaf_entry() and softleaf_from_pte() calls to ptep_zap_swap_entry() and pte_to_swp_entry() ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/mm/gmap_helpers.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/gmap_helpers.c +++ b/arch/s390/mm/gmap_helpers.c @@ -47,6 +47,7 @@ static void ptep_zap_swap_entry(struct m void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) { struct vm_area_struct *vma; + unsigned long pgstev; spinlock_t *ptl; pgste_t pgste; pte_t *ptep; @@ -65,9 +66,13 @@ void gmap_helper_zap_one_page(struct mm_ if (pte_swap(*ptep)) { preempt_disable(); pgste = pgste_get_lock(ptep); + pgstev = pgste_val(pgste);
- ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep)); - pte_clear(mm, vmaddr, ptep); + if ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED || + (pgstev & _PGSTE_GPS_ZERO)) { + ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep)); + pte_clear(mm, vmaddr, ptep); + }
pgste_set_unlock(ptep, pgste); preempt_enable();