netdev - Re: [PATCH net 2/2] net: bridge: fix lockdep multicast

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Message-ID: <20210426124806.4zqhtn4wewair4ua@gondor.apana.org.au>
Date:   Mon, 26 Apr 2021 20:48:06 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Nikolay Aleksandrov <nikolay@...dia.com>
Cc:     Taehee Yoo <ap420073@...il.com>, davem@...emloft.net,
        kuba@...nel.org, dsahern@...nel.org, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, j.vosburgh@...il.com, vfalico@...il.com,
        andy@...yhouse.net, roopa@...dia.com, ast@...nel.org,
        andriin@...com, daniel@...earbox.net, weiwan@...gle.com,
        cong.wang@...edance.com, bjorn@...nel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net 2/2] net: bridge: fix lockdep multicast_lock false
 positive splat

On Sun, Apr 25, 2021 at 07:45:27PM +0300, Nikolay Aleksandrov wrote:
>
> Ugh.. that's just very ugly. :) The setup you've described above is by all means invalid, but
> possible unfortunately. The bridge already checks if it's being added as a port to another
> bridge, but not through multiple levels of indirection. These locks are completely unrelated
> as they're in very different contexts (different devices).

Surely we should forbid this? Otherwise what's to stop someone
from creating a loop?

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt