The patch titled
Subject: mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic()
has been removed from the -mm tree. Its filename was
mm-userfaultfd-fix-missing-cache-flush-in-mcopy_atomic_pte-and-__mcopy_atomic.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic()
userfaultfd calls mcopy_atomic_pte() and __mcopy_atomic() which do not do
any cache flushing for the target page. Then the target page will be
mapped to the user space with a different address (user address), which
might have an alias issue with the kernel address used to copy the data
from the user to. Fix this by insert flush_dcache_page() after
copy_from_user() succeeds.
Link: https://lkml.kernel.org/r/20220210123058.79206-7-songmuchun@xxxxxxxxxxxxx
Fixes: b6ebaedb4cb1 ("userfaultfd: avoid mmap_sem read recursion in mcopy_atomic")
Fixes: c1a4de99fada ("userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Fam Zheng <fam.zheng@xxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lars Persson <lars.persson@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/userfaultfd.c~mm-userfaultfd-fix-missing-cache-flush-in-mcopy_atomic_pte-and-__mcopy_atomic
+++ a/mm/userfaultfd.c
@@ -150,6 +150,8 @@ static int mcopy_atomic_pte(struct mm_st
/* don't free the page */
goto out;
}
+
+ flush_dcache_page(page);
} else {
page = *pagep;
*pagep = NULL;
@@ -625,6 +627,7 @@ retry:
err = -EFAULT;
goto out;
}
+ flush_dcache_page(page);
goto retry;
} else
BUG_ON(page);
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
