# Re: \[PATCH v7 12/28\] fanotify: Support null inode event in fanotify\_dfid\_inode

- From: Amir Goldstein \<amir73il@gmail.com\>
- Date: 2021-10-15 05:49:14 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2021/10/216035
- Thread: https://ratatoskr.run/linux-fsdevel/2021/10/215996/t.md

```text
On Fri, Oct 15, 2021 at 12:38 AM Gabriel Krisman Bertazi
[ref] wrote:
>
> FAN_FS_ERROR doesn't support DFID, but this function is still called for
> every event.  The problem is that it is not capable of handling null
> inodes, which now can happen in case of superblock error events.  For
> this case, just returning dir will be enough.
>
> Signed-off-by: Gabriel Krisman Bertazi <redacted>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>


Please also fortify fsnotify_handle_inode_event() against calling
->handle_inode_event() with NULL inode.

> ---
>  fs/notify/fanotify/fanotify.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index c620b4f6fe12..397ee623ff1e 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -452,7 +452,7 @@ static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
>         if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
>                 return dir;
>
> -       if (S_ISDIR(inode->i_mode))
> +       if (inode && S_ISDIR(inode->i_mode))
>                 return inode;
>
>         return dir;
> --
> 2.33.0
>
```