[PATCH net 1/4] net/smc: take sock lock in smc_ioctl()

[PATCH net 1/4] net/smc: take sock lock in smc_ioctl()

[Ursula Braun]

From: Ursula Braun <ursula.braun@linux.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@gmail.com>
Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com
Signed-off-by: Ursula Braun <ubraun@linux.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)
@@ -1573,8 +1574,10 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd,
 		}
 		break;
 	default:
+		release_sock(&smc->sk);
 		return -ENOIOCTLCMD;
 	}
+	release_sock(&smc->sk);
 
 	return put_user(answ, (int __user *)arg);
 }
-- 
2.16.4

Re: [PATCH net 1/4] net/smc: take sock lock in smc_ioctl()

[Stefano Brivio]

On Mon, 16 Jul 2018 12:01:01 +0200
Ursula Braun <ubraun@linux.ibm.com> wrote:

> From: Ursula Braun <ursula.braun@linux.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@gmail.com>
> Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com
> Signed-off-by: Ursula Braun <ubraun@linux.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.

-- 
Stefano

Re: [PATCH net 1/4] net/smc: take sock lock in smc_ioctl()

[Ursula Braun]

On 07/16/2018 12:09 PM, Stefano Brivio wrote:
> On Mon, 16 Jul 2018 12:01:01 +0200
> Ursula Braun <ubraun@linux.ibm.com> wrote:
> 
>> From: Ursula Braun <ursula.braun@linux.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@gmail.com>
>> Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com
>> Signed-off-by: Ursula Braun <ubraun@linux.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.