ext4: check inline directory before converting

Before converting an inline directory to a regular directory, check
the directory entries to make sure they're not obviously broken.
This helps us to avoid a BUG_ON if one of the dirents is trashed.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>

3 files changed, 39 insertions, 0 deletions

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index ef1bed66c14f..0bb3f9ea0832 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -571,6 +571,31 @@ static int ext4_release_dir(struct inode *inode, struct file *filp)
         return 0;
 }
 
+int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
+                      int buf_size)
+{
+        struct ext4_dir_entry_2 *de;
+        int nlen, rlen;
+        unsigned int offset = 0;
+        char *top;
+
+        de = (struct ext4_dir_entry_2 *)buf;
+        top = buf + buf_size;
+        while ((char *) de < top) {
+                if (ext4_check_dir_entry(dir, NULL, de, bh,
+                                         buf, buf_size, offset))
+                        return -EIO;
+                nlen = EXT4_DIR_REC_LEN(de->name_len);
+                rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
+                de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
+                offset += rlen;
+        }
+        if ((char *) de > top)
+                return -EIO;
+
+        return 0;
+}
+
 const struct file_operations ext4_dir_operations = {
         .llseek         = ext4_dir_llseek,
         .read           = generic_read_dir,
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 321760d6b353..5b19760b1de5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2028,6 +2028,8 @@ static inline  unsigned char get_dtype(struct super_block *sb, int filetype)
 
         return ext4_filetype_table[filetype];
 }
+extern int ext4_check_all_de(struct inode *dir, struct buffer_head *bh,
+                             void *buf, int buf_size);
 
 /* fsync.c */
 extern int ext4_sync_file(struct file *, loff_t, loff_t, int);
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 141b6acbc51c..bea662bd0ca6 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1172,6 +1172,18 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
         if (error < 0)
                 goto out;
 
+        /*
+         * Make sure the inline directory entries pass checks before we try to
+         * convert them, so that we avoid touching stuff that needs fsck.
+         */
+        if (S_ISDIR(inode->i_mode)) {
+                error = ext4_check_all_de(inode, iloc->bh,
+                                        buf + EXT4_INLINE_DOTDOT_SIZE,
+                                        inline_size - EXT4_INLINE_DOTDOT_SIZE);
+                if (error)
+                        goto out;
+        }
+
         error = ext4_destroy_inline_data_nolock(handle, inode);
         if (error)
                 goto out;