From: Muchun Song songmuchun@bytedance.com
commit e763243cc6cb1fcc720ec58cfd6e7c35ae90a479 upstream.
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/20220210123058.79206-4-songmuchun@bytedance.com Fixes: fa4d75c1de13 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support") Signed-off-by: Muchun Song songmuchun@bytedance.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.com Cc: Axel Rasmussen axelrasmussen@google.com Cc: David Rientjes rientjes@google.com Cc: Fam Zheng fam.zheng@bytedance.com Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Lars Persson lars.persson@axis.com Cc: Peter Xu peterx@redhat.com Cc: Xiongchun Duan duanxiongchun@bytedance.com Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/memory.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/mm/memory.c +++ b/mm/memory.c @@ -4978,6 +4978,8 @@ long copy_huge_page_from_user(struct pag if (rc) break;
+ flush_dcache_page(subpage); + cond_resched(); } return ret_val;