This is a note to let you know that I've just added the patch titled
hugetlb: fix copy_huge_page_from_user contig page struct assumption
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hugetlb-fix-copy_huge_page_from_user-contig-page-struct-assumption.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3272cfc2525b3a2810a59312d7a1e6f04a0ca3ef Mon Sep 17 00:00:00 2001
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Date: Wed, 24 Feb 2021 12:07:54 -0800
Subject: hugetlb: fix copy_huge_page_from_user contig page struct assumption
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
commit 3272cfc2525b3a2810a59312d7a1e6f04a0ca3ef upstream.
page structs are not guaranteed to be contiguous for gigantic pages. The
routine copy_huge_page_from_user can encounter gigantic pages, yet it
assumes page structs are contiguous when copying pages from user space.
Since page structs for the target gigantic page are not contiguous, the
data copied from user space could overwrite other pages not associated
with the gigantic page and cause data corruption.
Non-contiguous page structs are generally not an issue. However, they can
exist with a specific kernel configuration and hotplug operations. For
example: Configure the kernel with CONFIG_SPARSEMEM and
!CONFIG_SPARSEMEM_VMEMMAP. Then, hotplug add memory for the area where
the gigantic page will be allocated.
Link: https://lkml.kernel.org/r/20210217184926.33567-2-mike.kravetz@xxxxxxxxxx
Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4793,17 +4793,19 @@ long copy_huge_page_from_user(struct pag
void *page_kaddr;
unsigned long i, rc = 0;
unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
+ struct page *subpage = dst_page;
- for (i = 0; i < pages_per_huge_page; i++) {
+ for (i = 0; i < pages_per_huge_page;
+ i++, subpage = mem_map_next(subpage, dst_page, i)) {
if (allow_pagefault)
- page_kaddr = kmap(dst_page + i);
+ page_kaddr = kmap(subpage);
else
- page_kaddr = kmap_atomic(dst_page + i);
+ page_kaddr = kmap_atomic(subpage);
rc = copy_from_user(page_kaddr,
(const void __user *)(src + i * PAGE_SIZE),
PAGE_SIZE);
if (allow_pagefault)
- kunmap(dst_page + i);
+ kunmap(subpage);
else
kunmap_atomic(page_kaddr);
Patches currently in stable-queue which might be from mike.kravetz@xxxxxxxxxx are
queue-4.14/hugetlb-fix-copy_huge_page_from_user-contig-page-struct-assumption.patch
queue-4.14/mm-hugetlb-fix-potential-double-free-in-hugetlb_regi.patch
queue-4.14/mm-hugetlb-fix-a-race-between-freeing-and-dissolving-the-page.patch
queue-4.14/mm-rmap-fix-potential-pte_unmap-on-an-not-mapped-pte.patch
