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authorMike Kravetz <mike.kravetz@oracle.com>2021-02-24 12:07:54 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:33 -0800
commit3272cfc2525b3a2810a59312d7a1e6f04a0ca3ef (patch)
tree55731ca09d2f293ad3ed0cbfc3e66530c449bcda /mm/memory.c
parentdbfee5aee7e54f83d96ceb8e3e80717fac62ad63 (diff)
hugetlb: fix copy_huge_page_from_user contig page struct assumption
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@oracle.com Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c
index ef4e10c60b5f..784249f3307b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5177,17 +5177,19 @@ long copy_huge_page_from_user(struct page *dst_page,
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);