netdev - Re: INFO: task hung in tls_sw_release_resources

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Date:   Fri, 16 Aug 2019 22:47:43 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Steffen Klassert <steffen.klassert@...unet.com>
Cc:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        syzbot <syzbot+6a9ff159672dfbb41c95@...kaller.appspotmail.com>,
        ast@...nel.org, aviadye@...lanox.com, borisp@...lanox.com,
        bpf@...r.kernel.org, daniel@...earbox.net, davejwatson@...com,
        davem@...emloft.net, hdanton@...a.com, john.fastabend@...il.com,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        herbert@...dor.apana.org.au, linux-crypto@...r.kernel.org
Subject: Re: INFO: task hung in tls_sw_release_resources_tx

[+Steffen, who is the maintainer of pcrypt]

On Fri, Aug 16, 2019 at 07:02:34PM -0700, Jakub Kicinski wrote:
> On Thu, 15 Aug 2019 11:06:00 -0700, syzbot wrote:
> > syzbot has bisected this bug to:
> > 
> > commit 130b392c6cd6b2aed1b7eb32253d4920babb4891
> > Author: Dave Watson <davejwatson@...com>
> > Date:   Wed Jan 30 21:58:31 2019 +0000
> > 
> >      net: tls: Add tls 1.3 support
> > 
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=118e8dee600000
> > start commit:   6d5afe20 sctp: fix memleak in sctp_send_reset_streams
> > git tree:       net
> > final crash:    https://syzkaller.appspot.com/x/report.txt?x=138e8dee600000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=158e8dee600000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=a4c9e9f08e9e8960
> > dashboard link: https://syzkaller.appspot.com/bug?extid=6a9ff159672dfbb41c95
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17cb0502600000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14d5dc22600000
> > 
> > Reported-by: syzbot+6a9ff159672dfbb41c95@...kaller.appspotmail.com
> > Fixes: 130b392c6cd6 ("net: tls: Add tls 1.3 support")
> > 
> > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> CC Herbert, linux-crypto
> 
> This is got to be something in the crypto code :S 
> 
> The test case opens a ktls socket and back log writes to it.
> Then it opens a AF_ALG socket, binds "pcrypt(gcm(aes))" and dies.
> 
> The ktls socket upon close waits for async crypto callbacks, but they
> never come. If I unset CRYPTO_USER_API_AEAD or change the alg to bind
> to "gcm(aes)" the bug does not trigger.
> 
> Any suggestions?

Seeing as pcrypt is involved and this is a "task hung" bug, this is probably
caused by the recursive pcrypt deadlock, which is yet to be fixed.

See the original thread for more info:

	https://groups.google.com/forum/#!msg/syzkaller-bugs/1_CXUd3gBcg/BvsRLH0lAgAJ

And the syzbot dashboard link:

	https://syzkaller.appspot.com/bug?id=178f2528d10720d563091fb51dceb4cb20f75525

Let's tell syzbot this is a duplicate:

#syz dup: INFO: task hung in aead_recvmsg


Steffen, do you have any plan to fix this?

- Eric