On Thu, Jan 12, 2023 at 01:32:48AM +0000, Peng Zhang wrote: > From: ZhangPeng <zhangpeng362@xxxxxxxxxx> > > Dan Carpenter reported a Smatch static checker warning: > > fs/ntfs3/namei.c:96 ntfs_lookup() > error: potential NULL/IS_ERR bug 'inode' > It will cause null-ptr-deref when dir_search_u() returns NULL if the > file is not found. > Fix this by replacing IS_ERR() with IS_ERR_OR_NULL() to add a check for > NULL. That's a bad approach - you are papering over bad calling conventions instead of fixing them. IS_ERR_OR_NULL is almost never the right tool. Occasionally there are valid cases for function possibly returning pointer/NULL/ERR_PTR(...); this is almost certainly not one of those. Incidentally, inodes with NULL ->i_op should never exist. _Any_ place that sets ->i_op to NULL is broken, plain and simple. A new instance of struct inode has ->i_op pointing to empty method table; it *is* initialized.
