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ext4: add more inode number paranoia checks

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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
This commit is contained in:
Theodore Ts'o 2018-06-17 00:41:14 -04:00
parent 8bc1379b82
commit c37e9e0134
3 changed files with 7 additions and 6 deletions
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5
fs/ext4/ext4.h
View File

@ -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)
{
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));
}

3
fs/ext4/inode.c
View File

@ -4506,7 +4506,8 @@ 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);

5
fs/ext4/super.c
View File

@ -3858,6 +3858,11 @@ 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)) {