From f9476fc04a26ab79d5e96688a1ecc1b8b822230a Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Thu, 2 Jun 2022 01:49:32 +0000 Subject: [PATCH] mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic() stable inclusion from stable-4.19.243 commit 259dfb503b8f4087898403faf0e76dcb8d232e3d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5A6BA CVE: NA -------------------------------- commit 7c25a0b89a487878b0691e6524fb5a8827322194 upstream. 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@bytedance.com 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 Cc: Axel Rasmussen Cc: David Rientjes Cc: Fam Zheng Cc: Kirill A. Shutemov Cc: Lars Persson Cc: Mike Kravetz Cc: Peter Xu Cc: Xiongchun Duan Cc: Zi Yan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yongqiang Liu --- mm/userfaultfd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index c26dd2040624..10fb16ac23e8 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -55,6 +55,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, /* don't free the page */ goto out; } + + flush_dcache_page(page); } else { page = *pagep; *pagep = NULL; @@ -601,6 +603,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, err = -EFAULT; goto out; } + flush_dcache_page(page); goto retry; } else BUG_ON(page); -- GitLab