Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 12 Jan 2023 03:43:31 +0000 | From | Al Viro <> | Subject | Re: [PATCH -next] fs/ntfs3: Fix potential NULL/IS_ERR bug in ntfs_lookup() |
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On Thu, Jan 12, 2023 at 01:32:48AM +0000, Peng Zhang wrote: > From: ZhangPeng <zhangpeng362@huawei.com> > > 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.
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