+ mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set.patch added to mm-hotfixes-unstable branch

+ mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/pagemap: fix wr-protect even if PM_SCAN_WP_MATCHING not set
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: mm/pagemap: fix wr-protect even if PM_SCAN_WP_MATCHING not set
Date: Thu, 16 Nov 2023 15:15:46 -0500

The new pagemap ioctl contains a fast path for wr-protections without
looking into category masks.  It forgets to check PM_SCAN_WP_MATCHING
before applying the wr-protections.  It can cause, e.g., pte markers
installed on archs that do not even support uffd wr-protect.

WARNING: CPU: 0 PID: 5059 at mm/memory.c:1520 zap_pte_range mm/memory.c:1520 [inline]

Link: https://lkml.kernel.org/r/20231116201547.536857-3-peterx@redhat.com
Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: syzbot+7ca4b2719dc742b8d0a4@syzkaller.appspotmail.com
Cc: Andrei Vagin <avagin@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/task_mmu.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/proc/task_mmu.c~mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set
+++ a/fs/proc/task_mmu.c
@@ -2156,7 +2156,7 @@ static int pagemap_scan_pmd_entry(pmd_t
 		return 0;
 	}
 
-	if (!p->vec_out) {
+	if ((p->arg.flags & PM_SCAN_WP_MATCHING) && !p->vec_out) {
 		/* Fast path for performing exclusive WP */
 		for (addr = start; addr != end; pte++, addr += PAGE_SIZE) {
 			if (pte_uffd_wp(ptep_get(pte)))
_

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

mm-pagemap-fix-ioctlpagemap_scan-on-vma-check.patch
mm-pagemap-fix-wr-protect-even-if-pm_scan_wp_matching-not-set.patch
mm-selftests-fix-pagemap_ioctl-memory-map-test.patch