From: Theodore Ts'o tytso@mit.edu
commit c37e9e013469521d9adb932d17a1795c139b36db upstream.
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 [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Hackmann ghackmann@google.com --- fs/ext4/ext4.h | 5 ----- fs/ext4/inode.c | 3 ++- fs/ext4/super.c | 5 +++++ 3 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index bd997b3d6a6f..beea7a33f5ee 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1386,11 +1386,6 @@ static inline struct timespec ext4_current_time(struct inode *inode) 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)); } diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index eb06f62fa95b..75dc9da78196 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3737,7 +3737,8 @@ static int __ext4_get_inode_loc(struct inode *inode, 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 -EIO;
iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 6806b8937803..a9e8df7c529f 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3794,6 +3794,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } 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)) {