1 files changed, 57 insertions, 16 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a630b27a4c..1311ad0464 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -151,10 +151,11 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
 
 		return bh;
 	}
-	if (!bh && (type == INDEX || type == DIRENT_HTREE)) {
+	/* The first directory block must not be a hole. */
+	if (!bh && (type == INDEX || type == DIRENT_HTREE || block == 0)) {
 		ext4_error_inode(inode, func, line, block,
-				 "Directory hole found for htree %s block",
-				 (type == INDEX) ? "index" : "leaf");
+				 "Directory hole found for htree %s block %u",
+				 (type == INDEX) ? "index" : "leaf", block);
 		return ERR_PTR(-EFSCORRUPTED);
 	}
 	if (!bh)
@@ -2217,6 +2218,52 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 	return err ? err : err2;
 }
 
+static bool ext4_check_dx_root(struct inode *dir, struct dx_root *root)
+{
+	struct fake_dirent *fde;
+	const char *error_msg;
+	unsigned int rlen;
+	unsigned int blocksize = dir->i_sb->s_blocksize;
+	char *blockend = (char *)root + dir->i_sb->s_blocksize;
+
+	fde = &root->dot;
+	if (unlikely(fde->name_len != 1)) {
+		error_msg = "invalid name_len for '.'";
+		goto corrupted;
+	}
+	if (unlikely(strncmp(root->dot_name, ".", fde->name_len))) {
+		error_msg = "invalid name for '.'";
+		goto corrupted;
+	}
+	rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize);
+	if (unlikely((char *)fde + rlen >= blockend)) {
+		error_msg = "invalid rec_len for '.'";
+		goto corrupted;
+	}
+
+	fde = &root->dotdot;
+	if (unlikely(fde->name_len != 2)) {
+		error_msg = "invalid name_len for '..'";
+		goto corrupted;
+	}
+	if (unlikely(strncmp(root->dotdot_name, "..", fde->name_len))) {
+		error_msg = "invalid name for '..'";
+		goto corrupted;
+	}
+	rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize);
+	if (unlikely((char *)fde + rlen >= blockend)) {
+		error_msg = "invalid rec_len for '..'";
+		goto corrupted;
+	}
+
+	return true;
+
+corrupted:
+	EXT4_ERROR_INODE(dir, "Corrupt dir, %s, running e2fsck is recommended",
+			 error_msg);
+	return false;
+}
+
 /*
  * This converts a one block unindexed directory to a 3 block indexed
  * directory, and adds the dentry to the indexed directory.
@@ -2251,17 +2298,17 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 		brelse(bh);
 		return retval;
 	}
+
 	root = (struct dx_root *) bh->b_data;
+	if (!ext4_check_dx_root(dir, root)) {
+		brelse(bh);
+		return -EFSCORRUPTED;
+	}
 
 	/* The 0th block becomes the root, move the dirents out */
 	fde = &root->dotdot;
 	de = (struct ext4_dir_entry_2 *)((char *)fde +
 		ext4_rec_len_from_disk(fde->rec_len, blocksize));
-	if ((char *) de >= (((char *) root) + blocksize)) {
-		EXT4_ERROR_INODE(dir, "invalid rec_len for '..'");
-		brelse(bh);
-		return -EFSCORRUPTED;
-	}
 	len = ((char *) root) + (blocksize - csum_size) - (char *) de;
 
 	/* Allocate new block for the 0th block's dirents */
@@ -3083,10 +3130,7 @@ bool ext4_empty_dir(struct inode *inode)
 		EXT4_ERROR_INODE(inode, "invalid size");
 		return false;
 	}
-	/* The first directory block must not be a hole,
-	 * so treat it as DIRENT_HTREE
-	 */
-	bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
+	bh = ext4_read_dirblock(inode, 0, EITHER);
 	if (IS_ERR(bh))
 		return false;
 
@@ -3531,10 +3575,7 @@ static struct buffer_head *ext4_get_first_dir_block(handle_t *handle,
 		struct ext4_dir_entry_2 *de;
 		unsigned int offset;
 
-		/* The first directory block must not be a hole, so
-		 * treat it as DIRENT_HTREE
-		 */
-		bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
+		bh = ext4_read_dirblock(inode, 0, EITHER);
 		if (IS_ERR(bh)) {
 			*retval = PTR_ERR(bh);
 			return NULL;