[PATCH net V2 1/1] net/smc: take sock lock in smc_ioctl()

Ursula Braun
2018-07-16T11:57:09Z

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 | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5334157f5065..c12a7fc18f56 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1524,10 +1524,13 @@ 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)
+ if (smc->sk.sk_state == SMC_LISTEN) {
+ release_sock(&smc->sk);
return -EINVAL;
+ }
if (smc->sk.sk_state == SMC_INIT ||
smc->sk.sk_state == SMC_CLOSED)
answ = 0;
@@ -1536,8 +1539,10 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd,
break;
case SIOCOUTQ:
/* output queue size (not send + not acked) */
- if (smc->sk.sk_state == SMC_LISTEN)
+ if (smc->sk.sk_state == SMC_LISTEN) {
+ release_sock(&smc->sk);
return -EINVAL;
+ }
if (smc->sk.sk_state == SMC_INIT ||
smc->sk.sk_state == SMC_CLOSED)
answ = 0;
@@ -1547,8 +1552,10 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd,
break;
case SIOCOUTQNSD:
/* output queue size (not send only) */
- if (smc->sk.sk_state == SMC_LISTEN)
+ if (smc->sk.sk_state == SMC_LISTEN) {
+ release_sock(&smc->sk);
return -EINVAL;
+ }
if (smc->sk.sk_state == SMC_INIT ||
smc->sk.sk_state == SMC_CLOSED)
answ = 0;
@@ -1556,8 +1563,10 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd,
answ = smc_tx_prepared_sends(&smc->conn);
break;
case SIOCATMARK:
- if (smc->sk.sk_state == SMC_LISTEN)
+ if (smc->sk.sk_state == SMC_LISTEN) {
+ release_sock(&smc->sk);
return -EINVAL;
+ }
if (smc->sk.sk_state == SMC_INIT ||
smc->sk.sk_state == SMC_CLOSED) {
answ = 0;
@@ -1573,8 +1582,10 @@ 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