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mm: Fix mremap not considering huge pmd devmap (CVE-2020-10757)

This commit is contained in:
Salvatore Bonaccorso 2020-06-05 12:34:01 +02:00
parent 50bf5b3b3d
commit 789f116fbc
3 changed files with 60 additions and 0 deletions
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1
debian/changelog vendored
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@ -14,6 +14,7 @@ linux (4.19.118-2+deb10u1) UNRELEASED; urgency=medium
(CVE-2020-10732)
* kernel/relay.c: handle alloc_percpu returning NULL in relay_open
(CVE-2019-19462)
* mm: Fix mremap not considering huge pmd devmap (CVE-2020-10757)
-- Salvatore Bonaccorso <carnil@debian.org> Thu, 28 May 2020 23:02:30 +0200

58
debian/patches/bugfix/all/mm-Fix-mremap-not-considering-huge-pmd-devmap.patch vendored Normal file
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@ -0,0 +1,58 @@
From: Fan Yang <Fan_Yang@sjtu.edu.cn>
Date: Thu, 4 Jun 2020 18:22:07 +0800
Subject: mm: Fix mremap not considering huge pmd devmap
Origin: https://git.kernel.org/linus/5bfea2d9b17f1034a68147a8b03b9789af5700f9
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2020-10757
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>
---
arch/x86/include/asm/pgtable.h | 1 +
mm/mremap.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
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() */
--
2.27.0.rc0

1
debian/patches/series vendored
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@ -309,5 +309,6 @@ bugfix/all/usb-gadget-fix-illegal-array-access-in-binding-with-.patch
bugfix/all/netlabel-cope-with-NULL-catmap.patch
bugfix/all/fs-binfmt_elf.c-allocate-initialized-memory-in-fill_.patch
bugfix/all/kernel-relay.c-handle-alloc_percpu-returning-NULL-in.patch
bugfix/all/mm-Fix-mremap-not-considering-huge-pmd-devmap.patch
# ABI maintenance