From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, david@redhat.com,
kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
mm-commits@vger.kernel.org, stable@vger.kernel.org,
torvalds@linux-foundation.org, yang.shi@linux.alibaba.com
Subject: [patch 09/15] khugepaged: fix null-pointer dereference due to race
Date: Thu, 23 Jul 2020 21:15:34 -0700 [thread overview]
Message-ID: <20200724041534.D87eQcPUp%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200723211432.b31831a0df3bc2cbdae31b40@linux-foundation.org>
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: khugepaged: fix null-pointer dereference due to race
khugepaged has to drop mmap lock several times while collapsing a page.
The situation can change while the lock is dropped and we need to
re-validate that the VMA is still in place and the PMD is still subject
for collapse.
But we miss one corner case: while collapsing an anonymous pages the VMA
could be replaced with file VMA. If the file VMA doesn't have any
private pages we get NULL pointer dereference:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
anon_vma_lock_write include/linux/rmap.h:120 [inline]
collapse_huge_page mm/khugepaged.c:1110 [inline]
khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline]
khugepaged_do_scan mm/khugepaged.c:2193 [inline]
khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238
The fix is to make sure that the VMA is anonymous in
hugepage_vma_revalidate(). The helper is only used for collapsing
anonymous pages.
Link: http://lkml.kernel.org/r/20200722121439.44328-1-kirill.shutemov@linux.intel.com
Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/khugepaged.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/khugepaged.c~khugepaged-fix-null-pointer-dereference-due-to-race
+++ a/mm/khugepaged.c
@@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struc
return SCAN_ADDRESS_RANGE;
if (!hugepage_vma_check(vma, vma->vm_flags))
return SCAN_VMA_CHECK;
+ /* Anon VMA expected */
+ if (!vma->anon_vma || vma->vm_ops)
+ return SCAN_VMA_CHECK;
return 0;
}
_
next prev parent reply other threads:[~2020-07-24 4:15 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-24 4:14 incoming Andrew Morton
2020-07-24 4:15 ` [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault Andrew Morton
2020-07-24 4:38 ` Yang Shi
2020-07-24 4:56 ` Andrew Morton
2020-07-24 19:27 ` Linus Torvalds
2020-07-24 20:22 ` Linus Torvalds
2020-07-25 0:36 ` Yang Shi
2020-07-25 1:29 ` Linus Torvalds
2020-07-25 15:58 ` Catalin Marinas
2020-07-28 9:22 ` Will Deacon
2020-07-28 9:39 ` Catalin Marinas
2020-07-28 10:07 ` Yu Xu
2020-07-28 11:46 ` Catalin Marinas
2020-07-28 10:21 ` Will Deacon
2020-07-28 18:28 ` Linus Torvalds
2020-07-27 17:52 ` Yang Shi
2020-07-27 18:04 ` Linus Torvalds
2020-07-27 18:42 ` Catalin Marinas
2020-07-27 20:56 ` Linus Torvalds
2020-07-27 22:34 ` Yang Shi
2020-07-27 7:31 ` Yu Xu
2020-07-27 11:05 ` Catalin Marinas
2020-07-27 17:01 ` Linus Torvalds
2020-07-28 11:19 ` Catalin Marinas
2020-07-27 17:12 ` Yu Xu
2020-07-27 18:04 ` Yang Shi
2020-07-27 18:37 ` Linus Torvalds
2020-07-27 22:43 ` Yang Shi
2020-07-28 0:38 ` Linus Torvalds
2020-07-28 0:13 ` Yu Xu
2020-07-28 10:53 ` Nicholas Piggin
2020-07-28 19:02 ` Linus Torvalds
2020-07-28 22:53 ` Nicholas Piggin
2020-07-29 13:58 ` Michael Ellerman
2020-07-28 6:41 ` Yu Xu
2020-07-24 4:15 ` [patch 02/15] mm/mmap.c: close race between munmap() and expand_upwards()/downwards() Andrew Morton
2020-07-24 4:15 ` [patch 03/15] vfs/xattr: mm/shmem: kernfs: release simple xattr entry in a right way Andrew Morton
2020-07-24 4:15 ` [patch 04/15] mm: initialize return of vm_insert_pages Andrew Morton
2020-07-24 4:15 ` [patch 05/15] mm/memcontrol: fix OOPS inside mem_cgroup_get_nr_swap_pages() Andrew Morton
2020-07-24 4:15 ` [patch 06/15] mm/memcg: fix refcount error while moving and swapping Andrew Morton
2020-07-24 13:41 ` Alex Shi
2020-07-24 4:15 ` [patch 07/15] mm: memcg/slab: fix memory leak at non-root kmem_cache destroy Andrew Morton
2020-07-24 4:15 ` [patch 08/15] mm/hugetlb: avoid hardcoding while checking if cma is enabled Andrew Morton
2020-07-24 4:15 ` Andrew Morton [this message]
2020-07-24 4:15 ` [patch 10/15] mailmap: add entry for Mike Rapoport Andrew Morton
2020-07-24 4:15 ` [patch 11/15] squashfs: fix length field overlap check in metadata reading Andrew Morton
2020-07-24 4:15 ` [patch 12/15] scripts/decode_stacktrace: strip basepath from all paths Andrew Morton
2020-07-24 4:15 ` [patch 13/15] io-mapping: indicate mapping failure Andrew Morton
2020-07-24 4:15 ` [patch 14/15] MAINTAINERS: add KCOV section Andrew Morton
2020-07-24 4:15 ` [patch 15/15] scripts/gdb: fix lx-symbols 'gdb.error' while loading modules Andrew Morton
2020-07-28 1:19 ` mmotm 2020-07-27-18-18 uploaded Andrew Morton
2020-07-28 2:14 ` Stephen Rothwell
2020-07-28 3:22 ` mmotm 2020-07-27-18-18 uploaded (drivers/scsi/ufs/: SCSI_UFS_EXYNOS) Randy Dunlap
2020-07-28 8:23 ` Alim Akhtar
2020-07-28 12:33 ` mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c) Randy Dunlap
2020-07-28 21:55 ` Andrew Morton
2020-07-28 22:20 ` Stephen Rothwell
2020-07-28 22:31 ` Andrew Morton
2020-07-29 14:18 ` Michael S. Tsirkin
2020-07-29 14:38 ` David Hildenbrand
2020-07-29 16:14 ` David Hildenbrand
2020-07-29 17:29 ` Randy Dunlap
2020-07-28 22:39 ` Randy Dunlap
2020-07-29 1:43 ` Nathan Chancellor
2020-07-29 1:44 ` Andrew Morton
2020-07-29 2:04 ` Randy Dunlap
2020-07-29 14:09 ` make oldconfig (Re: mmotm 2020-07-27-18-18 uploaded (mm/page_alloc.c)) Alexey Dobriyan
2020-07-31 23:46 ` mmotm 2020-07-31-16-45 uploaded Andrew Morton
2020-08-01 5:24 ` mmotm 2020-07-31-16-45 uploaded (drivers/staging/vc04_services/) Randy Dunlap
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