From 4980e837cab7e2acc4dad18dba656c6896c531aa Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Thu, 16 Nov 2023 15:15:46 -0500
Subject: [PATCH] mm/pagemap: fix wr-protect even if PM_SCAN_WP_MATCHING not
set
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
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrei Vagin <avagin@gmail.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(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index a6f88cbfb6897..435b61054b5b9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2156,7 +2156,7 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,
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)))
--
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