mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 12:57:53 +00:00
mm/userfaultfd: allow hugetlb change protection upon poison entry
commitc5977c95df
upstream. After UFFDIO_POISON, there can be two kinds of hugetlb pte markers, either the POISON one or UFFD_WP one. Allow change protection to run on a poisoned marker just like !hugetlb cases, ignoring the marker irrelevant of the permission. Here the two bits are mutual exclusive. For example, when install a poisoned entry it must not be UFFD_WP already (by checking pte_none() before such install). And it also means if UFFD_WP is set there must have no POISON bit set. It makes sense because UFFD_WP is a bit to reflect permission, and permissions do not apply if the pte is poisoned and destined to sigbus. So here we simply check uffd_wp bit set first, do nothing otherwise. Attach the Fixes to UFFDIO_POISON work, as before that it should not be possible to have poison entry for hugetlb (e.g., hugetlb doesn't do swap, so no chance of swapin errors). Link: https://lkml.kernel.org/r/20240405231920.1772199-1-peterx@redhat.com Link: https://lore.kernel.org/r/000000000000920d5e0615602dd1@google.com Fixes:fc71884a5f
("mm: userfaultfd: add new UFFDIO_POISON ioctl") Signed-off-by: Peter Xu <peterx@redhat.com> Reported-by: syzbot+b07c8ac8eee3d4d8440f@syzkaller.appspotmail.com Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: <stable@vger.kernel.org> [6.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
81cf85ae4f
commit
db01bfbddd
1 changed files with 7 additions and 3 deletions
10
mm/hugetlb.c
10
mm/hugetlb.c
|
@ -6653,9 +6653,13 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
|
|||
if (!pte_same(pte, newpte))
|
||||
set_huge_pte_at(mm, address, ptep, newpte, psize);
|
||||
} else if (unlikely(is_pte_marker(pte))) {
|
||||
/* No other markers apply for now. */
|
||||
WARN_ON_ONCE(!pte_marker_uffd_wp(pte));
|
||||
if (uffd_wp_resolve)
|
||||
/*
|
||||
* Do nothing on a poison marker; page is
|
||||
* corrupted, permissons do not apply. Here
|
||||
* pte_marker_uffd_wp()==true implies !poison
|
||||
* because they're mutual exclusive.
|
||||
*/
|
||||
if (pte_marker_uffd_wp(pte) && uffd_wp_resolve)
|
||||
/* Safe to modify directly (non-present->none). */
|
||||
huge_pte_clear(mm, address, ptep, psize);
|
||||
} else if (!huge_pte_none(pte)) {
|
||||
|
|
Loading…
Reference in a new issue