[PATCH 4/5] fs/ntfs3: Restore overflow checking for attr size in mi_enum_attr

[Konstantin Komarov]

Fixed comment.
Removed explicit initialization for INDEX_ROOT.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
---
 fs/ntfs3/index.c  | 7 ++++---
 fs/ntfs3/record.c | 5 +++++
 fs/ntfs3/super.c  | 2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 8718df791a55..9fefeac5fe7e 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -994,7 +994,7 @@ struct INDEX_ROOT *indx_get_root(struct ntfs_index 
*indx, struct ntfs_inode *ni,
     struct ATTR_LIST_ENTRY *le = NULL;
     struct ATTRIB *a;
     const struct INDEX_NAMES *in = &s_index_names[indx->type];
-    struct INDEX_ROOT *root = NULL;
+    struct INDEX_ROOT *root;

     a = ni_find_attr(ni, NULL, &le, ATTR_ROOT, in->name, in->name_len, 
NULL,
              mi);
@@ -1007,8 +1007,9 @@ struct INDEX_ROOT *indx_get_root(struct ntfs_index 
*indx, struct ntfs_inode *ni,
     root = resident_data_ex(a, sizeof(struct INDEX_ROOT));

     /* length check */
-    if (root && offsetof(struct INDEX_ROOT, ihdr) + 
le32_to_cpu(root->ihdr.used) >
-            le32_to_cpu(a->res.data_size)) {
+    if (root &&
+        offsetof(struct INDEX_ROOT, ihdr) + le32_to_cpu(root->ihdr.used) >
+            le32_to_cpu(a->res.data_size)) {
         return NULL;
     }

diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c
index abfe004774c0..0603169ee8a0 100644
--- a/fs/ntfs3/record.c
+++ b/fs/ntfs3/record.c
@@ -220,6 +220,11 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, 
struct ATTRIB *attr)
             return NULL;
         }

+        if (off + asize < off) {
+            /* Overflow check. */
+            return NULL;
+        }
+
         attr = Add2Ptr(attr, asize);
         off += asize;
     }
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 0967035146ce..19d0889b131f 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -1187,7 +1187,7 @@ static int ntfs_fill_super(struct super_block *sb, 
struct fs_context *fc)

     /*
      * Typical $AttrDef contains up to 20 entries.
-     * Check for extremely large size.
+     * Check for extremely large/small size.
      */
     if (inode->i_size < sizeof(struct ATTR_DEF_ENTRY) ||
         inode->i_size > 100 * sizeof(struct ATTR_DEF_ENTRY)) {
--
2.34.1