This is a note to let you know that I've just added the patch titled
s390/mm: validate VMA in PGSTE manipulation functions
to the 5.4-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-mm-validate-vma-in-pgste-manipulation-functions.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fe3d10024073f06f04c74b9674bd71ccc1d787cf Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@xxxxxxxxxx>
Date: Thu, 9 Sep 2021 18:22:42 +0200
Subject: s390/mm: validate VMA in PGSTE manipulation functions
From: David Hildenbrand <david@xxxxxxxxxx>
commit fe3d10024073f06f04c74b9674bd71ccc1d787cf upstream.
We should not walk/touch page tables outside of VMA boundaries when
holding only the mmap sem in read mode. Evil user space can modify the
VMA layout just before this function runs and e.g., trigger races with
page table removal code since commit dd2283f2605e ("mm: mmap: zap pages
with read mmap_sem in munmap"). gfn_to_hva() will only translate using
KVM memory regions, but won't validate the VMA.
Further, we should not allocate page tables outside of VMA boundaries: if
evil user space decides to map hugetlbfs to these ranges, bad things will
happen because we suddenly have PTE or PMD page tables where we
shouldn't have them.
Similarly, we have to check if we suddenly find a hugetlbfs VMA, before
calling get_locked_pte().
Fixes: 2d42f9477320 ("s390/kvm: Add PGSTE manipulation functions")
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/20210909162248.14969-4-david@xxxxxxxxxx
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/mm/pgtable.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -970,6 +970,7 @@ EXPORT_SYMBOL(get_guest_storage_key);
int pgste_perform_essa(struct mm_struct *mm, unsigned long hva, int orc,
unsigned long *oldpte, unsigned long *oldpgste)
{
+ struct vm_area_struct *vma;
unsigned long pgstev;
spinlock_t *ptl;
pgste_t pgste;
@@ -979,6 +980,10 @@ int pgste_perform_essa(struct mm_struct
WARN_ON_ONCE(orc > ESSA_MAX);
if (unlikely(orc > ESSA_MAX))
return -EINVAL;
+
+ vma = find_vma(mm, hva);
+ if (!vma || hva < vma->vm_start || is_vm_hugetlb_page(vma))
+ return -EFAULT;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
@@ -1071,10 +1076,14 @@ EXPORT_SYMBOL(pgste_perform_essa);
int set_pgste_bits(struct mm_struct *mm, unsigned long hva,
unsigned long bits, unsigned long value)
{
+ struct vm_area_struct *vma;
spinlock_t *ptl;
pgste_t new;
pte_t *ptep;
+ vma = find_vma(mm, hva);
+ if (!vma || hva < vma->vm_start || is_vm_hugetlb_page(vma))
+ return -EFAULT;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
@@ -1099,9 +1108,13 @@ EXPORT_SYMBOL(set_pgste_bits);
*/
int get_pgste(struct mm_struct *mm, unsigned long hva, unsigned long *pgstep)
{
+ struct vm_area_struct *vma;
spinlock_t *ptl;
pte_t *ptep;
+ vma = find_vma(mm, hva);
+ if (!vma || hva < vma->vm_start || is_vm_hugetlb_page(vma))
+ return -EFAULT;
ptep = get_locked_pte(mm, hva, &ptl);
if (unlikely(!ptep))
return -EFAULT;
Patches currently in stable-queue which might be from david@xxxxxxxxxx are
queue-5.4/proc-vmcore-fix-clearing-user-buffer-by-properly-using-clear_user.patch
queue-5.4/s390-mm-validate-vma-in-pgste-manipulation-functions.patch
