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 c8ad14c697c4a72da15f147061a419aefdf09356..f5d9f82b173a05d80d9998486bfe3a5efeaddb03 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1468,11 +1468,6 @@ 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 b8f4394971c89dda4fadd9956559e97cb2a297db..b507de0e4bbf42fd287da53c657b0a3856869e77 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3991,7 +3991,8 @@ 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 4cff3ff7b9e0db5a4d70779a07e59caf98096e55..9762fde91fb587ff02a0fc26eccf17dcfd053ec8 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3549,6 +3549,11 @@ 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)) {