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| author | Theodore Ts'o <tytso@mit.edu> | 2009-01-16 11:13:40 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-01-16 11:13:40 -0500 |
| commit | e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f (patch) | |
| tree | 07a439d21576794c5d39a06a86b09e690e55f2f2 | |
| parent | 06a279d636734da32bb62dd2f7b0ade666f65d7c (diff) | |
| download | linux-e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f.tar.gz linux-e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f.tar.bz2 linux-e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f.zip | |
ext4: 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.
Thanks to Sami Liedes for reporting this bug.
http://bugzilla.kernel.org/show_bug.cgi?id=12430
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
| -rw-r--r-- | fs/ext4/namei.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index fec0b4c2f5f1..ba702bd7910d 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1368,7 +1368,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, struct fake_dirent *fde; blocksize = dir->i_sb->s_blocksize; - dxtrace(printk(KERN_DEBUG "Creating index\n")); + dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino)); retval = ext4_journal_get_write_access(handle, bh); if (retval) { ext4_std_error(dir->i_sb, retval); @@ -1377,6 +1377,20 @@ 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 ext4_dir_entry_2 *)((char *)fde + + ext4_rec_len_from_disk(fde->rec_len)); + if ((char *) de >= (((char *) root) + blocksize)) { + ext4_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; + + /* Allocate new block for the 0th block's dirents */ bh2 = ext4_append(handle, dir, &block, &retval); if (!(bh2)) { brelse(bh); @@ -1385,11 +1399,6 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, EXT4_I(dir)->i_flags |= EXT4_INDEX_FL; data1 = bh2->b_data; - /* 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)); - len = ((char *) root) + blocksize - (char *) de; memcpy (data1, de, len); de = (struct ext4_dir_entry_2 *) data1; top = data1 + len; |