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KVM: s390: Fix gmap_helper_zap_one_page() again

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[ 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: 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>
[ 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>
This commit is contained in:
Claudio Imbrenda 2025-12-30 22:16:26 -05:00 committed by Greg Kroah-Hartman
parent 2a30b3c9ea
commit 2af2abbcbf
1 changed files with 7 additions and 2 deletions
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9
arch/s390/mm/gmap_helpers.c
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@ -47,6 +47,7 @@ static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
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_struct *mm, unsigned long vmaddr)
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();