netdev - Re: rtnl_mutex deadlock?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150806003026.GA12785@gondor.apana.org.au>
Date:	Thu, 6 Aug 2015 08:30:26 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jiri Pirko <jiri@...nulli.us>,
	Cong Wang <cwang@...pensource.com>,
	David Miller <davem@...emloft.net>,
	Nicolas Dichtel <nicolas.dichtel@...nd.com>,
	Thomas Graf <tgraf@...g.ch>, Scott Feldman <sfeldma@...il.com>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: rtnl_mutex deadlock?

On Wed, Aug 05, 2015 at 08:59:07PM +0200, Daniel Borkmann wrote:
>
> Here's a theory and patch below. Herbert, Thomas, does this make any
> sense to you resp. sound plausible? ;)

It's certainly possible.  Whether it's plausible I'm not so sure.
The netlink hashtable is unlimited in size.  So it should always
be expanding, not rehashing.  The bug you found should only affect
rehashing.

> I'm not quite sure what's best to return from here, i.e. whether we
> propagate -ENOMEM or instead retry over and over again hoping that the
> rehashing completed (and no new rehashing started in the mean time) ...

Please use something other than ENOMEM as it is already heavily
used in this context.  Perhaps EOVERFLOW?

We should probably add a WARN_ON_ONCE in rhashtable_insert_rehash
since two concurrent rehashings indicates something is going
seriously wrong.

Thanks,
-- 
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
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html