This is a note to let you know that I've just added the patch titled
mm/uffd: fix vma check on userfault for wp
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-uffd-fix-vma-check-on-userfault-for-wp.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 67eae54bc227b30dedcce9db68b063ba1adb7838 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@xxxxxxxxxx>
Date: Mon, 24 Oct 2022 15:33:35 -0400
Subject: mm/uffd: fix vma check on userfault for wp
From: Peter Xu <peterx@xxxxxxxxxx>
commit 67eae54bc227b30dedcce9db68b063ba1adb7838 upstream.
We used to have a report that pte-marker code can be reached even when
uffd-wp is not compiled in for file memories, here:
https://lore.kernel.org/all/YzeR+R6b4bwBlBHh@x1n/T/#u
I just got time to revisit this and found that the root cause is we simply
messed up with the vma check, so that for !PTE_MARKER_UFFD_WP system, we
will allow UFFDIO_REGISTER of MINOR & WP upon shmem as the check was
wrong:
if (vm_flags & VM_UFFD_MINOR)
return is_vm_hugetlb_page(vma) || vma_is_shmem(vma);
Where we'll allow anything to pass on shmem as long as minor mode is
requested.
Axel did it right when introducing minor mode but I messed it up in
b1f9e876862d when moving code around. Fix it.
Link: https://lkml.kernel.org/r/20221024193336.1233616-1-peterx@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20221024193336.1233616-2-peterx@xxxxxxxxxx
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/userfaultfd_k.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index f07e6998bb68..9df0b9a762cc 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -146,9 +146,9 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
static inline bool vma_can_userfault(struct vm_area_struct *vma,
unsigned long vm_flags)
{
- if (vm_flags & VM_UFFD_MINOR)
- return is_vm_hugetlb_page(vma) || vma_is_shmem(vma);
-
+ if ((vm_flags & VM_UFFD_MINOR) &&
+ (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
+ return false;
#ifndef CONFIG_PTE_MARKER_UFFD_WP
/*
* If user requested uffd-wp but not enabled pte markers for
--
2.38.1
Patches currently in stable-queue which might be from peterx@xxxxxxxxxx are
queue-6.0/mm-uffd-fix-vma-check-on-userfault-for-wp.patch
