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Commit a21102b5 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext3: Add sanity check to make_indexed_dir 

Make sure the rec_len field in the '..' entry is sane, lest we overrun
the directory block and cause a kernel oops on a purposefully
corrupted filesystem.

This fixes a bug related to a bug originally reported by Sami Liedes
for ext4 at:

http://bugzilla.kernel.org/show_bug.cgi?id=12430



Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
parent e6b8bc09

fs/ext3/namei.c

+14 −6
Original line number Diff line number Diff line
@@ -1358,7 +1358,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, 
	struct fake_dirent *fde;



	blocksize =  dir->i_sb->s_blocksize;

	dxtrace(printk("Creating index\n"));

	dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino));

	retval = ext3_journal_get_write_access(handle, bh);

	if (retval) {

		ext3_std_error(dir->i_sb, retval);
@@ -1367,6 +1367,19 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, 
	}

	root = (struct dx_root *) bh->b_data;



	/* The 0th block becomes the root, move the dirents out */

	fde = &root->dotdot;

	de = (struct ext3_dir_entry_2 *)((char *)fde +

			ext3_rec_len_from_disk(fde->rec_len));

	if ((char *) de >= (((char *) root) + blocksize)) {

		ext3_error(dir->i_sb, __func__,

			   "invalid rec_len for '..' in inode %lu",

			   dir->i_ino);

		brelse(bh);

		return -EIO;

	}

	len = ((char *) root) + blocksize - (char *) de;



	bh2 = ext3_append (handle, dir, &block, &retval);

	if (!(bh2)) {

		brelse(bh);
@@ -1375,11 +1388,6 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, 
	EXT3_I(dir)->i_flags |= EXT3_INDEX_FL;

	data1 = bh2->b_data;



	/* The 0th block becomes the root, move the dirents out */

	fde = &root->dotdot;

	de = (struct ext3_dir_entry_2 *)((char *)fde +

			ext3_rec_len_from_disk(fde->rec_len));

	len = ((char *) root) + blocksize - (char *) de;

	memcpy (data1, de, len);

	de = (struct ext3_dir_entry_2 *) data1;

	top = data1 + len;