linux-ext4 - [PATCH 4/5] ext4: add more inode number paranoia checks

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Date:   Sun, 17 Jun 2018 23:22:31 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     wen.xu@...ech.edu, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 4/5] ext4: add more inode number paranoia checks

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.

https://bugzilla.kernel.org/show_bug.cgi?id=200069

Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 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 859d6433dcc1..4bd69649a048 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -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));
 }
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c2f4ccb880c4..7d6c10017bdf 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4d34430d75f6..1f955c128e0d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -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)) {
-- 
2.18.0.rc0