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authorFan Yang <Fan_Yang@sjtu.edu.cn>2020-06-04 18:22:07 +0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 19:05:24 -0700
commit5bfea2d9b17f1034a68147a8b03b9789af5700f9 (patch)
treeedad86fc86a98a8f13c4ebd1c4cdc3beb2114435
parent15a2bc4dbb9cfed1c661a657fcb10798150b7598 (diff)
downloadlinux-5bfea2d9b17f1034a68147a8b03b9789af5700f9.tar.bz2
mm: Fix mremap not considering huge pmd devmap
The original code in mm/mremap.c checks huge pmd by: if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) { However, a DAX mapped nvdimm is mapped as huge page (by default) but it is not transparent huge page (_PAGE_PSE | PAGE_DEVMAP). This commit changes the condition to include the case. This addresses CVE-2020-10757. Fixes: 5c7fb56e5e3f ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd") Cc: <stable@vger.kernel.org> Reported-by: Fan Yang <Fan_Yang@sjtu.edu.cn> Signed-off-by: Fan Yang <Fan_Yang@sjtu.edu.cn> Tested-by: Fan Yang <Fan_Yang@sjtu.edu.cn> Tested-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/include/asm/pgtable.h1
-rw-r--r--mm/mremap.c2
2 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index f51d8997ed00..b8f46bbe69f4 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -257,6 +257,7 @@ static inline int pmd_large(pmd_t pte)
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/* NOTE: when predicate huge page, consider also pmd_devmap, or use pmd_large */
static inline int pmd_trans_huge(pmd_t pmd)
{
return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
diff --git a/mm/mremap.c b/mm/mremap.c
index 6aa6ea605068..57b1f999f789 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -266,7 +266,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
if (!new_pmd)
break;
- if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
+ if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd) || pmd_devmap(*old_pmd)) {
if (extent == HPAGE_PMD_SIZE) {
bool moved;
/* See comment in move_ptes() */