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

From: Ursula Braun <redacted>

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 <redacted>
Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com
Signed-off-by: Ursula Braun <redacted>
---
 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

On Mon, 16 Jul 2018 12:01:01 +0200
Ursula Braun [off-list ref] wrote:

                        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

On 07/16/2018 12:09 PM, Stefano Brivio wrote:

On Mon, 16 Jul 2018 12:01:01 +0200
Ursula Braun [off-list ref] wrote:

quoted

From: Ursula Braun <redacted>

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 <redacted>
Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com
Signed-off-by: Ursula Braun <redacted>
---
 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.