userfaultfd: shmem: add i_size checks

[linux-2.6-block.git] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index 6c54a6874e4143524f5305daaf1063d8a313c5a0..99d5867daadb1fb8341f585d91377c0619cf49aa 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2216,6 +2216,7 @@ 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))
@@ -2253,6 +2254,12 @@ 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_delay(page, dst_mm, gfp, &memcg, false);
        if (ret)
                goto out_release;
@@ -2268,8 +2275,14 @@ 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;
 
@@ -2287,13 +2300,14 @@ 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: