linux-ext4 - Re: [PATCH v7 12/28] fanotify: Support null inode event in fanotify_dfid

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Date:   Fri, 15 Oct 2021 08:49:01 +0300
From:   Amir Goldstein <amir73il@...il.com>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     Jan Kara <jack@...e.com>, "Darrick J. Wong" <djwong@...nel.org>,
        Theodore Tso <tytso@....edu>,
        David Howells <dhowells@...hat.com>,
        Khazhismel Kumykov <khazhy@...gle.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Ext4 <linux-ext4@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Matthew Bobrowski <repnop@...gle.com>, kernel@...labora.com
Subject: Re: [PATCH v7 12/28] fanotify: Support null inode event in fanotify_dfid_inode

On Fri, Oct 15, 2021 at 12:38 AM Gabriel Krisman Bertazi
<krisman@...labora.com> 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 <krisman@...labora.com>
Reviewed-by: Amir Goldstein <amir73il@...il.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
>