Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c37e9e01 authored Jun 17, 2018 by Theodore Ts'o

ext4: add more inode number paranoia checks

If there is a directory entry pointing to a system inode (such as a
journal inode), complain and declare the file system to be corrupted.

Also, if the superblock's first inode number field is too small,
refuse to mount the file system.

This addresses CVE-2018-10882.

https://bugzilla.kernel.org/show_bug.cgi?id=200069



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

parent 8bc1379b

fs/ext4/ext4.h

+0 −5

Original line number	Original line	Diff line number	Diff line
	@@ -1502,11 +1502,6 @@ static inline struct ext4_inode_info EXT4_I(struct inode inode)
	static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)		static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
	{		{
	return ino == EXT4_ROOT_INO \|\|		return ino == EXT4_ROOT_INO \|\|
	ino == EXT4_USR_QUOTA_INO \|\|
	ino == EXT4_GRP_QUOTA_INO \|\|
	ino == EXT4_BOOT_LOADER_INO \|\|
	ino == EXT4_JOURNAL_INO \|\|
	ino == EXT4_RESIZE_INO \|\|
	(ino >= EXT4_FIRST_INO(sb) &&		(ino >= EXT4_FIRST_INO(sb) &&
	ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));		ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));
	}		}

fs/ext4/inode.c

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -4506,7 +4506,8 @@ static int __ext4_get_inode_loc(struct inode *inode,
	int inodes_per_block, inode_offset;		int inodes_per_block, inode_offset;

	iloc->bh = NULL;		iloc->bh = NULL;
	if (!ext4_valid_inum(sb, inode->i_ino))		if (inode->i_ino < EXT4_ROOT_INO \|\|
			inode->i_ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
	return -EFSCORRUPTED;		return -EFSCORRUPTED;

	iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);		iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);

fs/ext4/super.c

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -3858,6 +3858,11 @@ static int ext4_fill_super(struct super_block sb, void data, int silent)
	} else {		} else {
	sbi->s_inode_size = le16_to_cpu(es->s_inode_size);		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
	sbi->s_first_ino = le32_to_cpu(es->s_first_ino);		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
			if (sbi->s_first_ino < EXT4_GOOD_OLD_FIRST_INO) {
			ext4_msg(sb, KERN_ERR, "invalid first ino: %u",
			sbi->s_first_ino);
			goto failed_mount;
			}
	if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) \|\|		if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) \|\|
	(!is_power_of_2(sbi->s_inode_size)) \|\|		(!is_power_of_2(sbi->s_inode_size)) \|\|
	(sbi->s_inode_size > blocksize)) {		(sbi->s_inode_size > blocksize)) {