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| author | Andrea Arcangeli <aarcange@redhat.com> | 2018-12-01 01:09:37 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-08 15:03:37 +0300 |
| commit | af3edb30cddfcc1eace505af10d08826a9522dbe (patch) | |
| tree | 73a0f659318a3ef9d80ff02c6d78e171dd65d8fd /mm/shmem.c | |
| parent | 683b47330c498a7bb90b1e863f63c9b5035dbba9 (diff) | |
| download | linux-af3edb30cddfcc1eace505af10d08826a9522dbe.tar.xz | |
userfaultfd: shmem: add i_size checks
commit e2a50c1f64145a04959df2442305d57307e5395a upstream.
With MAP_SHARED: recheck the i_size after taking the PT lock, to
serialize against truncate with the PT lock. Delete the page from the
pagecache if the i_size_read check fails.
With MAP_PRIVATE: check the i_size after the PT lock before mapping
anonymous memory or zeropages into the MAP_PRIVATE shmem mapping.
A mostly irrelevant cleanup: like we do the delete_from_page_cache()
pagecache removal after dropping the PT lock, the PT lock is a spinlock
so drop it before the sleepable page lock.
Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com
Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Reported-by: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 9f856ecda73b..581e7baf0478 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2244,6 +2244,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, struct page *page; pte_t _dst_pte, *dst_pte; int ret; + pgoff_t offset, max_off; ret = -ENOMEM; if (!shmem_inode_acct_block(inode, 1)) @@ -2281,6 +2282,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, __SetPageSwapBacked(page); __SetPageUptodate(page); + ret = -EFAULT; + offset = linear_page_index(dst_vma, dst_addr); + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(offset >= max_off)) + goto out_release; + ret = mem_cgroup_try_charge(page, dst_mm, gfp, &memcg, false); if (ret) goto out_release; @@ -2299,8 +2306,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (dst_vma->vm_flags & VM_WRITE) _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); - ret = -EEXIST; dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); + + ret = -EFAULT; + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(offset >= max_off)) + goto out_release_uncharge_unlock; + + ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock; @@ -2318,13 +2331,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); - unlock_page(page); pte_unmap_unlock(dst_pte, ptl); + unlock_page(page); ret = 0; out: return ret; out_release_uncharge_unlock: pte_unmap_unlock(dst_pte, ptl); + delete_from_page_cache(page); out_release_uncharge: mem_cgroup_cancel_charge(page, memcg, false); out_release: |