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@xxxxxxx> Suggested-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> --- fs/ext4/inode.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9d9f414f99fe..3f7cfa91ba89 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4872,13 +4872,6 @@ 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; @@ -4951,10 +4944,13 @@ 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 */ + if (flags & EXT4_IGET_SPECIAL) + ext4_error_inode(inode, function, line, 0, + "iget: special inode unallocated"); ret = -ESTALE; goto bad_inode; } -- 2.31.1
