diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index a630b27a4cc6..6917c1de8f41 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2217,6 +2217,52 @@ 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 +2297,17 @@ 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 */