netdev - Re: [PATCH net] team: avoid adding twice the same option to the event list

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Date:   Sun, 15 Apr 2018 21:53:38 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, jiri@...nulli.us
Subject: Re: [PATCH net] team: avoid adding twice the same option to the
 event list

On Fri, 2018-04-13 at 14:07 -0400, David Miller wrote:
> From: Paolo Abeni <pabeni@...hat.com>
> Date: Fri, 13 Apr 2018 13:59:25 +0200
> 
> > When parsing the options provided by the user space,
> > team_nl_cmd_options_set() insert them in a temporary list to send
> > multiple events with a single message.
> > While each option's attribute is correctly validated, the code does
> > not check for duplicate entries before inserting into the event
> > list.
> > 
> > Exploiting the above, the syzbot was able to trigger the following
> > splat:
>  ...
> > This changeset addresses the avoiding list_add() if the current
> > option is already present in the event list.
> > 
> > Reported-and-tested-by: syzbot+4d4af685432dc0e56c91@...kaller.appspotmail.com
> > Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> > Fixes: 2fcdb2c9e659 ("team: allow to send multiple set events in one message")
> 
> Looks good to me.
> 
> It's too bad that the tmp list entries don't get marked as they are
> added, or get unlinked by the list processor.  Either scheme would
> make the "already added" test a lot simpler.

Yes, I considered both changes, but than opted for this solution,
beliving it would be less invasive and more suitable for -net.

Cheers,

Paolo