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authorRyan Roberts <ryan.roberts@arm.com>2024-01-23 14:17:55 +0000
committerAndrew Morton <akpm@linux-foundation.org>2024-02-07 21:20:33 -0800
commit56ae10cf628b02279980d17439c6241a643959c2 (patch)
tree609fc879bf1a6b622980e3c155c62fc769f3058e /mm/userfaultfd.c
parentc1be35a16b2f1fe21f4f26f9de030ad6eaaf6a25 (diff)
mm/userfaultfd: UFFDIO_MOVE implementation should use ptep_get()
Commit c33c794828f2 ("mm: ptep_get() conversion") converted all (non-arch) call sites to use ptep_get() instead of doing a direct dereference of the pte. Full rationale can be found in that commit's log. Since then, UFFDIO_MOVE has been implemented which does 7 direct pte dereferences. Let's fix those up to use ptep_get(). I've asserted in the past that there is no reliable automated mechanism to catch these; I'm relying on a combination of Coccinelle (which throws up a lot of false positives) and some compiler magic to force a compiler error on dereference. But given the frequency with which new issues are coming up, I'll add it to my todo list to try to find an automated solution. Link: https://lkml.kernel.org/r/20240123141755.3836179-1-ryan.roberts@arm.com Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/userfaultfd.c')
-rw-r--r--mm/userfaultfd.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 75fcf1f783bc..7cf7d4384259 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -902,8 +902,8 @@ static int move_present_pte(struct mm_struct *mm,
double_pt_lock(dst_ptl, src_ptl);
- if (!pte_same(*src_pte, orig_src_pte) ||
- !pte_same(*dst_pte, orig_dst_pte)) {
+ if (!pte_same(ptep_get(src_pte), orig_src_pte) ||
+ !pte_same(ptep_get(dst_pte), orig_dst_pte)) {
err = -EAGAIN;
goto out;
}
@@ -946,8 +946,8 @@ static int move_swap_pte(struct mm_struct *mm,
double_pt_lock(dst_ptl, src_ptl);
- if (!pte_same(*src_pte, orig_src_pte) ||
- !pte_same(*dst_pte, orig_dst_pte)) {
+ if (!pte_same(ptep_get(src_pte), orig_src_pte) ||
+ !pte_same(ptep_get(dst_pte), orig_dst_pte)) {
double_pt_unlock(dst_ptl, src_ptl);
return -EAGAIN;
}
@@ -1016,7 +1016,7 @@ retry:
}
spin_lock(dst_ptl);
- orig_dst_pte = *dst_pte;
+ orig_dst_pte = ptep_get(dst_pte);
spin_unlock(dst_ptl);
if (!pte_none(orig_dst_pte)) {
err = -EEXIST;
@@ -1024,7 +1024,7 @@ retry:
}
spin_lock(src_ptl);
- orig_src_pte = *src_pte;
+ orig_src_pte = ptep_get(src_pte);
spin_unlock(src_ptl);
if (pte_none(orig_src_pte)) {
if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES))
@@ -1054,7 +1054,7 @@ retry:
* page isn't freed under us
*/
spin_lock(src_ptl);
- if (!pte_same(orig_src_pte, *src_pte)) {
+ if (!pte_same(orig_src_pte, ptep_get(src_pte))) {
spin_unlock(src_ptl);
err = -EAGAIN;
goto out;