ext4: add more inode number paranoia checks

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>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index db389611f8bcf44446507b741763bd80e1380fc4..0abb30d19fa18b8fb463615ee785caf9f9d0a8db 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1542,11 +1542,6 @@ static inline struct ext4_inode_info *EXT4_I(struct inode *inode)
 static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 {
        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 5b28153eb0fdd8a06665fe1ab184b2b2c8748f43..c2efe4d2ad872f5d6e024d57f019aa8807c3231c 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4455,7 +4455,8 @@ 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 -EFSCORRUPTED;
 
        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 fefcfa9fe40869ae535510b796d733b71425759a..6933efbb582faa609c6e628d59cd297524fa8fbd 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3811,6 +3811,11 @@ 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)) {