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/inode.c b/fs/ext4/inode.c
index 81b16c3..5c4c9af 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4242,7 +4242,8 @@
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);