[merged mm-stable] drivers-misc-open-dice-dont-touch-vm_mayshare.patch removed from -mm tree

[merged mm-stable] drivers-misc-open-dice-dont-touch-vm_mayshare.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: drivers/misc/open-dice: don't touch VM_MAYSHARE
has been removed from the -mm tree.  Its filename was
     drivers-misc-open-dice-dont-touch-vm_mayshare.patch

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

------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: drivers/misc/open-dice: don't touch VM_MAYSHARE
Date: Mon, 2 Jan 2023 17:08:56 +0100

A MAP_SHARED mapping always has VM_MAYSHARE set, and writable
(VM_MAYWRITE) MAP_SHARED mappings have VM_SHARED set as well.  To identify
a MAP_SHARED mapping, it's sufficient to look at VM_MAYSHARE.

We cannot have VM_MAYSHARE|VM_WRITE mappings without having VM_SHARED set.
Consequently, current code will never actually end up clearing
VM_MAYSHARE and that code is confusing, because nobody is supposed to mess
with VM_MAYWRITE.

Let's clean it up and restructure the code. No functional change intended.

Link: https://lkml.kernel.org/r/20230102160856.500584-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/misc/open-dice.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- a/drivers/misc/open-dice.c~drivers-misc-open-dice-dont-touch-vm_mayshare
+++ a/drivers/misc/open-dice.c
@@ -90,15 +90,13 @@ static int open_dice_mmap(struct file *f
 {
 	struct open_dice_drvdata *drvdata = to_open_dice_drvdata(filp);
 
-	/* Do not allow userspace to modify the underlying data. */
-	if ((vma->vm_flags & VM_WRITE) && (vma->vm_flags & VM_SHARED))
-		return -EPERM;
-
-	/* Ensure userspace cannot acquire VM_WRITE + VM_SHARED later. */
-	if (vma->vm_flags & VM_WRITE)
-		vma->vm_flags &= ~VM_MAYSHARE;
-	else if (vma->vm_flags & VM_SHARED)
+	if (vma->vm_flags & VM_MAYSHARE) {
+		/* Do not allow userspace to modify the underlying data. */
+		if (vma->vm_flags & VM_WRITE)
+			return -EPERM;
+		/* Ensure userspace cannot acquire VM_WRITE later. */
 		vma->vm_flags &= ~VM_MAYWRITE;
+	}
 
 	/* Create write-combine mapping so all clients observe a wipe. */
 	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
_

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

mm-debug_vm_pgtable-more-pte_swp_exclusive-sanity-checks.patch
mm-debug_vm_pgtable-more-pte_swp_exclusive-sanity-checks-fix.patch
alpha-mm-support-__have_arch_pte_swp_exclusive.patch
arc-mm-support-__have_arch_pte_swp_exclusive.patch
arm-mm-support-__have_arch_pte_swp_exclusive.patch
csky-mm-support-__have_arch_pte_swp_exclusive.patch
hexagon-mm-support-__have_arch_pte_swp_exclusive.patch
ia64-mm-support-__have_arch_pte_swp_exclusive.patch
loongarch-mm-support-__have_arch_pte_swp_exclusive.patch
m68k-mm-remove-dummy-__swp-definitions-for-nommu.patch
m68k-mm-support-__have_arch_pte_swp_exclusive.patch
microblaze-mm-support-__have_arch_pte_swp_exclusive.patch
mips-mm-support-__have_arch_pte_swp_exclusive.patch
nios2-mm-refactor-swap-pte-layout.patch
nios2-mm-support-__have_arch_pte_swp_exclusive.patch
openrisc-mm-support-__have_arch_pte_swp_exclusive.patch
parisc-mm-support-__have_arch_pte_swp_exclusive.patch
powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s.patch
powerpc-nohash-mm-support-__have_arch_pte_swp_exclusive.patch
riscv-mm-support-__have_arch_pte_swp_exclusive.patch
sh-mm-support-__have_arch_pte_swp_exclusive.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-32bit.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-64bit.patch
um-mm-support-__have_arch_pte_swp_exclusive.patch
x86-mm-support-__have_arch_pte_swp_exclusive-also-on-32bit.patch
xtensa-mm-support-__have_arch_pte_swp_exclusive.patch
mm-remove-__have_arch_pte_swp_exclusive.patch