59 lines
2.2 KiB
Diff
59 lines
2.2 KiB
Diff
From: Fan Yang <Fan_Yang@sjtu.edu.cn>
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Date: Thu, 4 Jun 2020 18:22:07 +0800
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Subject: mm: Fix mremap not considering huge pmd devmap
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Origin: https://git.kernel.org/linus/5bfea2d9b17f1034a68147a8b03b9789af5700f9
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2020-10757
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The original code in mm/mremap.c checks huge pmd by:
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if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
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However, a DAX mapped nvdimm is mapped as huge page (by default) but it
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is not transparent huge page (_PAGE_PSE | PAGE_DEVMAP). This commit
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changes the condition to include the case.
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This addresses CVE-2020-10757.
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Fixes: 5c7fb56e5e3f ("mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd")
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Cc: <stable@vger.kernel.org>
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Reported-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
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Signed-off-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
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Tested-by: Fan Yang <Fan_Yang@sjtu.edu.cn>
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Tested-by: Dan Williams <dan.j.williams@intel.com>
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Reviewed-by: Dan Williams <dan.j.williams@intel.com>
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Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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arch/x86/include/asm/pgtable.h | 1 +
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mm/mremap.c | 2 +-
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2 files changed, 2 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
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index f51d8997ed00..b8f46bbe69f4 100644
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--- a/arch/x86/include/asm/pgtable.h
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+++ b/arch/x86/include/asm/pgtable.h
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@@ -257,6 +257,7 @@ static inline int pmd_large(pmd_t pte)
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}
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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+/* NOTE: when predicate huge page, consider also pmd_devmap, or use pmd_large */
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static inline int pmd_trans_huge(pmd_t pmd)
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{
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return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
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diff --git a/mm/mremap.c b/mm/mremap.c
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index 6aa6ea605068..57b1f999f789 100644
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--- a/mm/mremap.c
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+++ b/mm/mremap.c
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@@ -266,7 +266,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
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new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
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if (!new_pmd)
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break;
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- if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
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+ if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd) || pmd_devmap(*old_pmd)) {
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if (extent == HPAGE_PMD_SIZE) {
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bool moved;
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/* See comment in move_ptes() */
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--
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2.27.0.rc0
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