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KVM: s390: Fix gmap_helper_zap_one_page() again 

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: 5deafa27d9 ("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>
pull/1354/merge
Claudio Imbrenda 2025-11-04 16:40:48 +01:00 committed by Heiko Carstens
parent f770950a47
commit 2f393c228c
1 changed files with 7 additions and 2 deletions
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9
arch/s390/mm/gmap_helpers.c
View File

@ -47,6 +47,7 @@ static void ptep_zap_softleaf_entry(struct mm_struct *mm, softleaf_t entry)
void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr)
{ {
struct vm_area_struct *vma; struct vm_area_struct *vma;
unsigned long pgstev;
spinlock_t *ptl; spinlock_t *ptl;
pgste_t pgste; pgste_t pgste;
pte_t *ptep; pte_t *ptep;
@ -65,9 +66,13 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr)
if (pte_swap(*ptep)) { if (pte_swap(*ptep)) {
preempt_disable(); preempt_disable();
pgste = pgste_get_lock(ptep); pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste);
ptep_zap_softleaf_entry(mm, softleaf_from_pte(*ptep)); if ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
pte_clear(mm, vmaddr, ptep); (pgstev & _PGSTE_GPS_ZERO)) {
ptep_zap_softleaf_entry(mm, softleaf_from_pte(*ptep));
pte_clear(mm, vmaddr, ptep);
}
pgste_set_unlock(ptep, pgste); pgste_set_unlock(ptep, pgste);
preempt_enable(); preempt_enable();