[merged mm-hotfixes-stable] mm-secretmem-fix-gup-fast-succeeding-on-secretmem-folios.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/secretmem: fix GUP-fast succeeding on secretmem folios
has been removed from the -mm tree.  Its filename was
     mm-secretmem-fix-gup-fast-succeeding-on-secretmem-folios.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: mm/secretmem: fix GUP-fast succeeding on secretmem folios
Date: Mon, 25 Mar 2024 14:41:12 +0100

folio_is_secretmem() states that secretmem folios cannot be LRU folios: so
we may only exit early if we find an LRU folio.  Yet, we exit early if we
find a folio that is not a secretmem folio.

Consequently, folio_is_secretmem() fails to detect secretmem folios and,
therefore, we can succeed in grabbing a secretmem folio during GUP-fast,
crashing the kernel when we later try reading/writing to the folio,
because the folio has been unmapped from the directmap.

Link: https://lkml.kernel.org/r/20240325134114.257544-2-david@redhat.com
Fixes: 1507f51255c9 ("mm: introduce memfd_secret system call to create "secret" memory areas")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Closes: https://lore.kernel.org/lkml/CABOYnLyevJeravW=QrH0JUPYEcDN160aZFb7kwndm-J2rmz0HQ@mail.gmail.com/
Debugged-by: Miklos Szeredi <miklos@szeredi.hu>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/secretmem.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/secretmem.h~mm-secretmem-fix-gup-fast-succeeding-on-secretmem-folios
+++ a/include/linux/secretmem.h
@@ -16,7 +16,7 @@ static inline bool folio_is_secretmem(st
 	 * We know that secretmem pages are not compound and LRU so we can
 	 * save a couple of cycles here.
 	 */
-	if (folio_test_large(folio) || !folio_test_lru(folio))
+	if (folio_test_large(folio) || folio_test_lru(folio))
 		return false;
 
 	mapping = (struct address_space *)
_

Patches currently in -mm which might be from david@redhat.com are

mm-madvise-make-madv_populate_readwrite-handle-vm_fault_retry-properly.patch
mm-madvise-dont-perform-madvise-vma-walk-for-madv_populate_readwrite.patch
mm-userfaultfd-dont-place-zeropages-when-zeropages-are-disallowed.patch
s390-mm-re-enable-the-shared-zeropage-for-pv-and-skeys-kvm-guests.patch
mm-convert-folio_estimated_sharers-to-folio_likely_mapped_shared.patch
mm-convert-folio_estimated_sharers-to-folio_likely_mapped_shared-fix.patch
selftests-memfd_secret-add-vmsplice-test.patch
mm-merge-folio_is_secretmem-into-folio_fast_pin_allowed.patch