netdev - Re: [PATCH net] rhashtable: prevent work queue schedule while dismantling

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20181001134022.jpcunwro5nvvrbkr@gondor.apana.org.au>
Date:   Mon, 1 Oct 2018 21:40:22 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Thomas Graf <tgraf@...g.ch>
Subject: Re: [PATCH net] rhashtable: prevent work queue schedule while
 dismantling

On Mon, Oct 01, 2018 at 06:16:27AM -0700, Eric Dumazet wrote:
> syszbot found an interesting use-after-free [1] happening
> while IPv4 fragment rhashtable was destroyed at netns dismantle.
> 
> While no insertions can possibly happen at the time a dismantling
> netns is destroying this rhashtable, timers can still fire and
> attempt to remove elements from this rhashtable.

Hmm, I think that's your real problem.  rhashtable_free_and_destroy
doesn't take any locks with respect to the normal insertion/removal
path so it definitely isn't safe to call it while you're still
invoking the normal rhashtable remove function.

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