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Commit a72d7f83 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

ext4: Avoid rec_len overflow with 64KB block size 



With 64KB blocksize, a directory entry can have size 64KB which does not fit
into 16 bits we have for entry lenght. So we store 0xffff instead and convert
value when read from / written to disk. The patch also converts some places
to use ext4_next_entry() when we are changing them anyway.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
parent afc7cbca

fs/ext4/dir.c

+6 −6
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ int ext4_check_dir_entry (const char * function, struct inode * dir, 
			  unsigned long offset)

{

	const char * error_msg = NULL;

	const int rlen = le16_to_cpu(de->rec_len);

	const int rlen = ext4_rec_len_from_disk(de->rec_len);



	if (rlen < EXT4_DIR_REC_LEN(1))

		error_msg = "rec_len is smaller than minimal";
@@ -172,10 +172,10 @@ static int ext4_readdir(struct file * filp, 
				 * least that it is non-zero.  A

				 * failure will be detected in the

				 * dirent test below. */

				if (le16_to_cpu(de->rec_len) <

						EXT4_DIR_REC_LEN(1))

				if (ext4_rec_len_from_disk(de->rec_len)

						< EXT4_DIR_REC_LEN(1))

					break;

				i += le16_to_cpu(de->rec_len);

				i += ext4_rec_len_from_disk(de->rec_len);

			}

			offset = i;

			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
@@ -197,7 +197,7 @@ static int ext4_readdir(struct file * filp, 
				ret = stored;

				goto out;

			}

			offset += le16_to_cpu(de->rec_len);

			offset += ext4_rec_len_from_disk(de->rec_len);

			if (le32_to_cpu(de->inode)) {

				/* We might block in the next section

				 * if the data destination is
@@ -219,7 +219,7 @@ static int ext4_readdir(struct file * filp, 
					goto revalidate;

				stored ++;

			}

			filp->f_pos += le16_to_cpu(de->rec_len);

			filp->f_pos += ext4_rec_len_from_disk(de->rec_len);

		}

		offset = 0;

		brelse (bh);

fs/ext4/namei.c

+37 −40
Original line number Diff line number Diff line
@@ -280,7 +280,7 @@ static struct stats dx_show_leaf(struct dx_hash_info *hinfo, struct ext4_dir_ent 
			space += EXT4_DIR_REC_LEN(de->name_len);

			names++;

		}

		de = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));

		de = ext4_next_entry(de);

	}

	printk("(%i)\n", names);

	return (struct stats) { names, space, 1 };
@@ -551,7 +551,8 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash, 
 */

static inline struct ext4_dir_entry_2 *ext4_next_entry(struct ext4_dir_entry_2 *p)

{

	return (struct ext4_dir_entry_2 *)((char*)p + le16_to_cpu(p->rec_len));

	return (struct ext4_dir_entry_2 *)((char *)p +

		ext4_rec_len_from_disk(p->rec_len));

}



/*
@@ -720,7 +721,7 @@ static int dx_make_map (struct ext4_dir_entry_2 *de, int size, 
			cond_resched();

		}

		/* XXX: do we need to check rec_len == 0 case? -Chris */

		de = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));

		de = ext4_next_entry(de);

	}

	return count;

}
@@ -820,7 +821,7 @@ static inline int search_dirblock(struct buffer_head * bh, 
			return 1;

		}

		/* prevent looping on a bad block */

		de_len = le16_to_cpu(de->rec_len);

		de_len = ext4_rec_len_from_disk(de->rec_len);

		if (de_len <= 0)

			return -1;

		offset += de_len;
@@ -1128,7 +1129,7 @@ dx_move_dirents(char *from, char *to, struct dx_map_entry *map, int count) 
		rec_len = EXT4_DIR_REC_LEN(de->name_len);

		memcpy (to, de, rec_len);

		((struct ext4_dir_entry_2 *) to)->rec_len =

				cpu_to_le16(rec_len);

				ext4_rec_len_to_disk(rec_len);

		de->inode = 0;

		map++;

		to += rec_len;
@@ -1147,13 +1148,12 @@ static struct ext4_dir_entry_2* dx_pack_dirents(char *base, int size) 


	prev = to = de;

	while ((char*)de < base + size) {

		next = (struct ext4_dir_entry_2 *) ((char *) de +

						    le16_to_cpu(de->rec_len));

		next = ext4_next_entry(de);

		if (de->inode && de->name_len) {

			rec_len = EXT4_DIR_REC_LEN(de->name_len);

			if (de > to)

				memmove(to, de, rec_len);

			to->rec_len = cpu_to_le16(rec_len);

			to->rec_len = ext4_rec_len_to_disk(rec_len);

			prev = to;

			to = (struct ext4_dir_entry_2 *) (((char *) to) + rec_len);

		}
@@ -1227,8 +1227,8 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir, 
	/* Fancy dance to stay within two buffers */

	de2 = dx_move_dirents(data1, data2, map + split, count - split);

	de = dx_pack_dirents(data1,blocksize);

	de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de);

	de2->rec_len = cpu_to_le16(data2 + blocksize - (char *) de2);

	de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de);

	de2->rec_len = ext4_rec_len_to_disk(data2 + blocksize - (char *) de2);

	dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data1, blocksize, 1));

	dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1));
@@ -1297,7 +1297,7 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry, 
				return -EEXIST;

			}

			nlen = EXT4_DIR_REC_LEN(de->name_len);

			rlen = le16_to_cpu(de->rec_len);

			rlen = ext4_rec_len_from_disk(de->rec_len);

			if ((de->inode? rlen - nlen: rlen) >= reclen)

				break;

			de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
@@ -1316,11 +1316,11 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry, 


	/* By now the buffer is marked for journaling */

	nlen = EXT4_DIR_REC_LEN(de->name_len);

	rlen = le16_to_cpu(de->rec_len);

	rlen = ext4_rec_len_from_disk(de->rec_len);

	if (de->inode) {

		struct ext4_dir_entry_2 *de1 = (struct ext4_dir_entry_2 *)((char *)de + nlen);

		de1->rec_len = cpu_to_le16(rlen - nlen);

		de->rec_len = cpu_to_le16(nlen);

		de1->rec_len = ext4_rec_len_to_disk(rlen - nlen);

		de->rec_len = ext4_rec_len_to_disk(nlen);

		de = de1;

	}

	de->file_type = EXT4_FT_UNKNOWN;
@@ -1397,17 +1397,18 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, 


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

	fde = &root->dotdot;

	de = (struct ext4_dir_entry_2 *)((char *)fde + le16_to_cpu(fde->rec_len));

	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;

	while ((char *)(de2=(void*)de+le16_to_cpu(de->rec_len)) < top)

	while ((char *)(de2 = ext4_next_entry(de)) < top)

		de = de2;

	de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de);

	de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de);

	/* Initialize the root; the dot dirents already exist */

	de = (struct ext4_dir_entry_2 *) (&root->dotdot);

	de->rec_len = cpu_to_le16(blocksize - EXT4_DIR_REC_LEN(2));

	de->rec_len = ext4_rec_len_to_disk(blocksize - EXT4_DIR_REC_LEN(2));

	memset (&root->info, 0, sizeof(root->info));

	root->info.info_length = sizeof(root->info);

	root->info.hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;
@@ -1487,7 +1488,7 @@ static int ext4_add_entry (handle_t *handle, struct dentry *dentry, 
		return retval;

	de = (struct ext4_dir_entry_2 *) bh->b_data;

	de->inode = 0;

	de->rec_len = cpu_to_le16(blocksize);

	de->rec_len = ext4_rec_len_to_disk(blocksize);

	return add_dirent_to_buf(handle, dentry, inode, de, bh);

}
@@ -1550,7 +1551,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry, 
			goto cleanup;

		node2 = (struct dx_node *)(bh2->b_data);

		entries2 = node2->entries;

		node2->fake.rec_len = cpu_to_le16(sb->s_blocksize);

		node2->fake.rec_len = ext4_rec_len_to_disk(sb->s_blocksize);

		node2->fake.inode = 0;

		BUFFER_TRACE(frame->bh, "get_write_access");

		err = ext4_journal_get_write_access(handle, frame->bh);
@@ -1648,9 +1649,9 @@ static int ext4_delete_entry (handle_t *handle, 
			BUFFER_TRACE(bh, "get_write_access");

			ext4_journal_get_write_access(handle, bh);

			if (pde)

				pde->rec_len =

					cpu_to_le16(le16_to_cpu(pde->rec_len) +

						    le16_to_cpu(de->rec_len));

				pde->rec_len = ext4_rec_len_to_disk(

					ext4_rec_len_from_disk(pde->rec_len) +

					ext4_rec_len_from_disk(de->rec_len));

			else

				de->inode = 0;

			dir->i_version++;
@@ -1658,10 +1659,9 @@ static int ext4_delete_entry (handle_t *handle, 
			ext4_journal_dirty_metadata(handle, bh);

			return 0;

		}

		i += le16_to_cpu(de->rec_len);

		i += ext4_rec_len_from_disk(de->rec_len);

		pde = de;

		de = (struct ext4_dir_entry_2 *)

			((char *) de + le16_to_cpu(de->rec_len));

		de = ext4_next_entry(de);

	}

	return -ENOENT;

}
@@ -1824,13 +1824,13 @@ static int ext4_mkdir(struct inode * dir, struct dentry * dentry, int mode) 
	de = (struct ext4_dir_entry_2 *) dir_block->b_data;

	de->inode = cpu_to_le32(inode->i_ino);

	de->name_len = 1;

	de->rec_len = cpu_to_le16(EXT4_DIR_REC_LEN(de->name_len));

	de->rec_len = ext4_rec_len_to_disk(EXT4_DIR_REC_LEN(de->name_len));

	strcpy (de->name, ".");

	ext4_set_de_type(dir->i_sb, de, S_IFDIR);

	de = (struct ext4_dir_entry_2 *)

			((char *) de + le16_to_cpu(de->rec_len));

	de = ext4_next_entry(de);

	de->inode = cpu_to_le32(dir->i_ino);

	de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize-EXT4_DIR_REC_LEN(1));

	de->rec_len = ext4_rec_len_to_disk(inode->i_sb->s_blocksize -

						EXT4_DIR_REC_LEN(1));

	de->name_len = 2;

	strcpy (de->name, "..");

	ext4_set_de_type(dir->i_sb, de, S_IFDIR);
@@ -1882,8 +1882,7 @@ static int empty_dir (struct inode * inode) 
		return 1;

	}

	de = (struct ext4_dir_entry_2 *) bh->b_data;

	de1 = (struct ext4_dir_entry_2 *)

			((char *) de + le16_to_cpu(de->rec_len));

	de1 = ext4_next_entry(de);

	if (le32_to_cpu(de->inode) != inode->i_ino ||

			!le32_to_cpu(de1->inode) ||

			strcmp (".", de->name) ||
@@ -1894,9 +1893,9 @@ static int empty_dir (struct inode * inode) 
		brelse (bh);

		return 1;

	}

	offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len);

	de = (struct ext4_dir_entry_2 *)

			((char *) de1 + le16_to_cpu(de1->rec_len));

	offset = ext4_rec_len_from_disk(de->rec_len) +

		 ext4_rec_len_from_disk(de1->rec_len);

	de = ext4_next_entry(de1);

	while (offset < inode->i_size ) {

		if (!bh ||

			(void *) de >= (void *) (bh->b_data+sb->s_blocksize)) {
@@ -1925,9 +1924,8 @@ static int empty_dir (struct inode * inode) 
			brelse (bh);

			return 0;

		}

		offset += le16_to_cpu(de->rec_len);

		de = (struct ext4_dir_entry_2 *)

				((char *) de + le16_to_cpu(de->rec_len));

		offset += ext4_rec_len_from_disk(de->rec_len);

		de = ext4_next_entry(de);

	}

	brelse (bh);

	return 1;
@@ -2282,8 +2280,7 @@ static int ext4_link (struct dentry * old_dentry, 
}



#define PARENT_INO(buffer) \

	((struct ext4_dir_entry_2 *) ((char *) buffer + \

	le16_to_cpu(((struct ext4_dir_entry_2 *) buffer)->rec_len)))->inode

	(ext4_next_entry((struct ext4_dir_entry_2 *)(buffer))->inode)



/*

 * Anybody can rename anything with this: the permission checks are left to the

include/linux/ext4_fs.h

+20 −0
Original line number Diff line number Diff line
@@ -767,6 +767,26 @@ struct ext4_dir_entry_2 { 
#define EXT4_DIR_ROUND			(EXT4_DIR_PAD - 1)

#define EXT4_DIR_REC_LEN(name_len)	(((name_len) + 8 + EXT4_DIR_ROUND) & \

					 ~EXT4_DIR_ROUND)

#define EXT4_MAX_REC_LEN		((1<<16)-1)



static inline unsigned ext4_rec_len_from_disk(__le16 dlen)

{

	unsigned len = le16_to_cpu(dlen);



	if (len == EXT4_MAX_REC_LEN)

		return 1 << 16;

	return len;

}



static inline __le16 ext4_rec_len_to_disk(unsigned len)

{

	if (len == (1 << 16))

		return cpu_to_le16(EXT4_MAX_REC_LEN);

	else if (len > (1 << 16))

		BUG();

	return cpu_to_le16(len);

}



/*

 * Hash Tree Directory indexing

 * (c) Daniel Phillips, 2001