Commit 4980e837 authored by Peter Xu's avatar Peter Xu Committed by Andrew Morton
Browse files

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: 12f6b01a ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag")
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Reported-by: default avatar <syzbot+7ca4b2719dc742b8d0a4@syzkaller.appspotmail.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarAndrei Vagin <avagin@gmail.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0dff1b40

fs/proc/task_mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -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)))