From: Theodore Ts'o Date: Sun, 17 Jun 2018 00:41:14 -0400 Subject: ext4: add more inode number paranoia checks Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit?id=a0b4bd6c4418a8d2ba51f27968f5af005e5dbbdd Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-10882 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 --- fs/ext4/ext4.h | 5 ----- fs/ext4/inode.c | 3 ++- fs/ext4/super.c | 5 +++++ 3 files changed, 7 insertions(+), 6 deletions(-) --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1501,11 +1501,6 @@ static inline struct ext4_inode_info *EX static inline int ext4_valid_inum(struct super_block *sb, unsigned long 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 <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count)); } --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4506,7 +4506,8 @@ static int __ext4_get_inode_loc(struct i int inodes_per_block, inode_offset; 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; iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb); --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3817,6 +3817,11 @@ static int ext4_fill_super(struct super_ } else { sbi->s_inode_size = le16_to_cpu(es->s_inode_size); 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) || (!is_power_of_2(sbi->s_inode_size)) || (sbi->s_inode_size > blocksize)) {