[068/227] mm: hugetlb: fix missing cache flush in copy_huge_page_from_user()

Commit Message

Andrew Morton March 22, 2022, 9:41 p.m. UTC

From: Muchun Song <[e-mail]>
Subject: mm: hugetlb: fix missing cache flush in copy_huge_page_from_user()

userfaultfd calls copy_huge_page_from_user() which does 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 issue by flushing dcache in copy_huge_page_from_user().

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: fa4d75c1de13 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support")
Signed-off-by: Muchun Song <[e-mail]>
Reviewed-by: Mike Kravetz <[e-mail]>
Cc: Axel Rasmussen <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Fam Zheng <[e-mail]>
Cc: Kirill A. Shutemov <[e-mail]>
Cc: Lars Persson <[e-mail]>
Cc: Peter Xu <[e-mail]>
Cc: Xiongchun Duan <[e-mail]>
Cc: Zi Yan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory.c |    2 ++
 1 file changed, 2 insertions(+)

Patch

--- a/mm/memory.c~mm-hugetlb-fix-missing-cache-flush-in-copy_huge_page_from_user
+++ a/mm/memory.c
@@ -5444,6 +5444,8 @@  long copy_huge_page_from_user(struct pag
 		if (rc)
 			break;
 
+		flush_dcache_page(subpage);
+
 		cond_resched();
 	}
 	return ret_val;