The patch titled
Subject: mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock(): fix
has been added to the -mm mm-unstable branch. Its filename is
mm-khugepaged-collapse_pte_mapped_thp-with-mmap_read_lock-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-collapse_pte_mapped_thp-with-mmap_read_lock-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock(): fix
Date: Sun, 23 Jul 2023 15:32:27 -0700 (PDT)
madvise_collapse() setting "mmap_locked = true" after calling
collapse_pte_mapped_thp() looked good but was wrong. If the loop then
moves on to the next extent, mmap_locked assures it that "vma" has been
revalidated under mmap_lock, which was not the case: and led to UAFs,
crashes in __fput() or task_work_run(), even collapse_file()'s
VM_BUG_ON(start & (HPAGE_PMD_NR - 1)) - all detected by syzbot.
(collapse_pte_mapped_thp() does validate the vma that it works on: but
it's not passed in as an argument, collapse_pte_mapped_thp() finds the vma
for mm and addr by itself - which may by this time have changed from the
vma saved in madvise_collapse().)
Link: https://lkml.kernel.org/r/d3d9ff14-ef8-8f84-e160-bfa1f5794275@xxxxxxxxxx
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Reported-by: syzbot+fe7b1487405295d29268@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/lkml/000000000000f9de430600ae05db@xxxxxxxxxx/
Reported-by: syzbot+173cc8cfdfbbef6dd755@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/linux-mm/000000000000e4b0f0060123ca40@xxxxxxxxxx/
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Huang, Ying <ying.huang@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Zack Rusin <zackr@xxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/khugepaged.c~mm-khugepaged-collapse_pte_mapped_thp-with-mmap_read_lock-fix
+++ a/mm/khugepaged.c
@@ -2840,7 +2840,7 @@ handle_result:
BUG_ON(*prev);
mmap_read_lock(mm);
result = collapse_pte_mapped_thp(mm, addr, true);
- mmap_locked = true;
+ mmap_read_unlock(mm);
goto handle_result;
/* Whitelisted set of results where continuing OK */
case SCAN_PMD_NULL:
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
tmpfs-fix-documentation-of-noswap-and-huge-mount-options.patch
shmem-minor-fixes-to-splice-read-implementation.patch
mm-pagewalk-fix-efi_pgt_dump-of-espfix-area.patch
mm-userfaultfd-add-new-uffdio_poison-ioctl-fix.patch
mm-pgtable-add-rcu_read_lock-and-rcu_read_unlocks.patch
mm-pgtable-add-pae-safety-to-__pte_offset_map.patch
arm-adjust_pte-use-pte_offset_map_nolock.patch
powerpc-assert_pte_locked-use-pte_offset_map_nolock.patch
powerpc-assert_pte_locked-use-pte_offset_map_nolock-fix.patch
powerpc-add-pte_free_defer-for-pgtables-sharing-page.patch
sparc-add-pte_free_defer-for-pte_t-pgtable_t.patch
s390-add-pte_free_defer-for-pgtables-sharing-page.patch
s390-add-pte_free_defer-for-pgtables-sharing-page-fix.patch
mm-pgtable-add-pte_free_defer-for-pgtable-as-page.patch
mm-khugepaged-retract_page_tables-without-mmap-or-vma-lock.patch
mm-khugepaged-collapse_pte_mapped_thp-with-mmap_read_lock.patch
mm-khugepaged-collapse_pte_mapped_thp-with-mmap_read_lock-fix.patch
mm-khugepaged-delete-khugepaged_collapse_pte_mapped_thps.patch
mm-khugepaged-delete-khugepaged_collapse_pte_mapped_thps-fix.patch
mm-delete-mmap_write_trylock-and-vma_try_start_write.patch
mm-pgtable-notes-on-pte_offset_map.patch
