diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-09-20 00:44:01 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-09-20 01:36:16 +0300 |
| commit | c131f751ab1a852d4dd4b490b3a7fbba7d738de5 (patch) | |
| tree | 8aad30641286414906d71e5bcfa7f8274998a601 /mm/khugepaged.c | |
| parent | d8e3875431956c1f78e142d531f490f76c760ce3 (diff) | |
| download | linux-c131f751ab1a852d4dd4b490b3a7fbba7d738de5.tar.xz | |
khugepaged: fix use-after-free in collapse_huge_page()
hugepage_vma_revalidate() tries to re-check if we still should try to
collapse small pages into huge one after the re-acquiring mmap_sem.
The problem Dmitry Vyukov reported[1] is that the vma found by
hugepage_vma_revalidate() can be suitable for huge pages, but not the
same vma we had before dropping mmap_sem. And dereferencing original
vma can lead to fun results..
Let's use vma hugepage_vma_revalidate() found instead of assuming it's the
same as what we had before the lock was dropped.
[1] http://lkml.kernel.org/r/CACT4Y+Z3gigBvhca9kRJFcjX0G70V_nRhbwKBU+yGoESBDKi9Q@mail.gmail.com
Link: http://lkml.kernel.org/r/20160907122559.GA6542@black.fi.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 79c52d0061af..62339bf3c726 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -838,7 +838,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) * value (scan code). */ -static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address) +static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, + struct vm_area_struct **vmap) { struct vm_area_struct *vma; unsigned long hstart, hend; @@ -846,7 +847,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address) if (unlikely(khugepaged_test_exit(mm))) return SCAN_ANY_PROCESS; - vma = find_vma(mm, address); + *vmap = vma = find_vma(mm, address); if (!vma) return SCAN_VMA_NULL; @@ -898,7 +899,7 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ if (ret & VM_FAULT_RETRY) { down_read(&mm->mmap_sem); - if (hugepage_vma_revalidate(mm, address)) { + if (hugepage_vma_revalidate(mm, address, &fe.vma)) { /* vma is no longer available, don't continue to swapin */ trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); return false; @@ -923,7 +924,6 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, static void collapse_huge_page(struct mm_struct *mm, unsigned long address, struct page **hpage, - struct vm_area_struct *vma, int node, int referenced) { pmd_t *pmd, _pmd; @@ -933,6 +933,7 @@ static void collapse_huge_page(struct mm_struct *mm, spinlock_t *pmd_ptl, *pte_ptl; int isolated = 0, result = 0; struct mem_cgroup *memcg; + struct vm_area_struct *vma; unsigned long mmun_start; /* For mmu_notifiers */ unsigned long mmun_end; /* For mmu_notifiers */ gfp_t gfp; @@ -961,7 +962,7 @@ static void collapse_huge_page(struct mm_struct *mm, } down_read(&mm->mmap_sem); - result = hugepage_vma_revalidate(mm, address); + result = hugepage_vma_revalidate(mm, address, &vma); if (result) { mem_cgroup_cancel_charge(new_page, memcg, true); up_read(&mm->mmap_sem); @@ -994,7 +995,7 @@ static void collapse_huge_page(struct mm_struct *mm, * handled by the anon_vma lock + PG_lock. */ down_write(&mm->mmap_sem); - result = hugepage_vma_revalidate(mm, address); + result = hugepage_vma_revalidate(mm, address, &vma); if (result) goto out; /* check if the pmd is still valid */ @@ -1202,7 +1203,7 @@ out_unmap: if (ret) { node = khugepaged_find_target_node(); /* collapse_huge_page will return with the mmap_sem released */ - collapse_huge_page(mm, address, hpage, vma, node, referenced); + collapse_huge_page(mm, address, hpage, node, referenced); } out: trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, |