Added additional checking for size of $AttrDef.
Added comment.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
---
  fs/ntfs3/super.c | 10 +++++++++-
  1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index ef4ea3f21905..0967035146ce 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -1185,10 +1185,18 @@ static int ntfs_fill_super(struct super_block 
*sb, struct fs_context *fc)
          goto out;
      }

-    if (inode->i_size < sizeof(struct ATTR_DEF_ENTRY)) {
+    /*
+     * Typical $AttrDef contains up to 20 entries.
+     * Check for extremely large size.
+     */
+    if (inode->i_size < sizeof(struct ATTR_DEF_ENTRY) ||
+        inode->i_size > 100 * sizeof(struct ATTR_DEF_ENTRY)) {
+        ntfs_err(sb, "Looks like $AttrDef is corrupted (size=%llu).",
+             inode->i_size);
          err = -EINVAL;
          goto put_inode_out;
      }
+
      bytes = inode->i_size;
      sbi->def_table = t = kmalloc(bytes, GFP_NOFS | __GFP_NOWARN);
      if (!t) {
-- 
2.34.1