From: Baokun Li libaokun1@huawei.com
[ Upstream commit 5cd740287ae5e3f9d1c46f5bfe8778972fd6d3fe ]
In ext4_fill_super(), EXT4_ORPHAN_FS flag is cleared after ext4_orphan_cleanup() is executed. Therefore, when __ext4_iget() is called to get an inode whose i_nlink is 0 when the flag exists, no error is returned. If the inode is a special inode, a null pointer dereference may occur. If the value of i_nlink is 0 for any inodes (except boot loader inodes) got by using the EXT4_IGET_SPECIAL flag, the current file system is corrupted. Therefore, make the ext4_iget() function return an error if it gets such an abnormal special inode.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=199179 Link: https://bugzilla.kernel.org/show_bug.cgi?id=216541 Link: https://bugzilla.kernel.org/show_bug.cgi?id=216539 Reported-by: Luís Henriques lhenriques@suse.de Suggested-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20230107032126.4165860-2-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/inode.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 3c7bbdaa425a7..6f1a3d8a8e825 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4942,13 +4942,6 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, goto bad_inode; raw_inode = ext4_raw_inode(&iloc);
- if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) { - ext4_error_inode(inode, function, line, 0, - "iget: root inode unallocated"); - ret = -EFSCORRUPTED; - goto bad_inode; - } - if ((flags & EXT4_IGET_HANDLE) && (raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) { ret = -ESTALE; @@ -5019,11 +5012,16 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, * NeilBrown 1999oct15 */ if (inode->i_nlink == 0) { - if ((inode->i_mode == 0 || + if ((inode->i_mode == 0 || flags & EXT4_IGET_SPECIAL || !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) && ino != EXT4_BOOT_LOADER_INO) { - /* this inode is deleted */ - ret = -ESTALE; + /* this inode is deleted or unallocated */ + if (flags & EXT4_IGET_SPECIAL) { + ext4_error_inode(inode, function, line, 0, + "iget: special inode unallocated"); + ret = -EFSCORRUPTED; + } else + ret = -ESTALE; goto bad_inode; } /* The only unlinked inodes we let through here have