linux-kernel - Re: [PATCH net 1/4] net/smc: take sock lock in smc

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Message-Id: <11a146f0-eebc-ece9-ed2b-32ad9a32a687@linux.ibm.com>
Date:   Mon, 16 Jul 2018 13:56:42 +0200
From:   Ursula Braun <ubraun@...ux.ibm.com>
To:     Stefano Brivio <sbrivio@...hat.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, raspl@...ux.ibm.com,
        linux-kernel@...r.kernel.org, eric.dumazet@...il.com,
        lifeasageek@...il.com
Subject: Re: [PATCH net 1/4] net/smc: take sock lock in smc_ioctl()



On 07/16/2018 12:09 PM, Stefano Brivio wrote:
> On Mon, 16 Jul 2018 12:01:01 +0200
> Ursula Braun <ubraun@...ux.ibm.com> wrote:
> 
>> From: Ursula Braun <ursula.braun@...ux.ibm.com>
>>
>> SMC ioctl processing requires the sock lock to work properly in
>> all thinkable scenarios.
>> Problem has been found with RaceFuzzer and fixes:
>>    KASAN: null-ptr-deref Read in smc_ioctl
>>
>> Reported-by: Byoungyoung Lee <lifeasageek@...il.com>
>> Reported-by: syzbot+35b2c5aa76fd398b9fd4@...kaller.appspotmail.com
>> Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
>> ---
>>  net/smc/af_smc.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>> index 5334157f5065..a4381b38a521 100644
>> --- a/net/smc/af_smc.c
>> +++ b/net/smc/af_smc.c
>> @@ -1524,6 +1524,7 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd,
>>  			return -EBADF;
>>  		return smc->clcsock->ops->ioctl(smc->clcsock, cmd, arg);
>>  	}
>> +	lock_sock(&smc->sk);
>>  	switch (cmd) {
>>  	case SIOCINQ: /* same as FIONREAD */
>>  		if (smc->sk.sk_state == SMC_LISTEN)
> 
>                         return -EINVAL;
> 
> you should also unlock here, and:
> 
>         case SIOCOUTQ:
>                 /* output queue size (not send + not acked) */
>                 if (smc->sk.sk_state == SMC_LISTEN)
>                         return -EINVAL;
> 
> here, and:
> 
>         case SIOCOUTQNSD:
>                 /* output queue size (not send only) */
>                 if (smc->sk.sk_state == SMC_LISTEN)
>                         return -EINVAL;
> 
> here, and:
> 
>         case SIOCATMARK:
>                 if (smc->sk.sk_state == SMC_LISTEN)
>                         return -EINVAL;
> 
> here.
> 

sorry, my fault! V2 is on its way. Thanks for your hint.