Merge branch 'net-smc-fixes-2022-04-08'

Karsten Graul says:

====================
net/smc: fixes 2022-04-08

Patch 1 fixes two usages of snprintf() with non null-terminated
string which results into an out-of-bounds read.
Pach 2 fixes a syzbot finding where a pointer check was missed
before the call to dev_name().
Patch 3 fixes a crash when already released memory is used as
a function pointer.
====================

Link: https://lore.kernel.org/r/20220408151035.1044701-1-kgraul@linux.ibm.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/smc/af_smc.c

@@ -121,6 +121,7 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
 					  bool *own_req)
 {
 	struct smc_sock *smc;
+	struct sock *child;
 
 	smc = smc_clcsock_user_data(sk);
 
@@ -134,8 +135,17 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
 	}
 
 	/* passthrough to original syn recv sock fct */
-	return smc->ori_af_ops->syn_recv_sock(sk, skb, req, dst, req_unhash,
-					      own_req);
+	child = smc->ori_af_ops->syn_recv_sock(sk, skb, req, dst, req_unhash,
+					       own_req);
+	/* child must not inherit smc or its ops */
+	if (child) {
+		rcu_assign_sk_user_data(child, NULL);
+
+		/* v4-mapped sockets don't inherit parent ops. Don't restore. */
+		if (inet_csk(child)->icsk_af_ops == inet_csk(sk)->icsk_af_ops)
+			inet_csk(child)->icsk_af_ops = smc->ori_af_ops;
+	}
+	return child;
 
 drop:
 	dst_release(dst);

net/smc/smc_clc.c

@@ -191,7 +191,8 @@ static int smc_nl_ueid_dumpinfo(struct sk_buff *skb, u32 portid, u32 seq,
 			  flags, SMC_NETLINK_DUMP_UEID);
 	if (!hdr)
 		return -ENOMEM;
-	snprintf(ueid_str, sizeof(ueid_str), "%s", ueid);
+	memcpy(ueid_str, ueid, SMC_MAX_EID_LEN);
+	ueid_str[SMC_MAX_EID_LEN] = 0;
 	if (nla_put_string(skb, SMC_NLA_EID_TABLE_ENTRY, ueid_str)) {
 		genlmsg_cancel(skb, hdr);
 		return -EMSGSIZE;
@@ -252,7 +253,8 @@ int smc_nl_dump_seid(struct sk_buff *skb, struct netlink_callback *cb)
 		goto end;
 
 	smc_ism_get_system_eid(&seid);
-	snprintf(seid_str, sizeof(seid_str), "%s", seid);
+	memcpy(seid_str, seid, SMC_MAX_EID_LEN);
+	seid_str[SMC_MAX_EID_LEN] = 0;
 	if (nla_put_string(skb, SMC_NLA_SEID_ENTRY, seid_str))
 		goto err;
 	read_lock(&smc_clc_eid_table.lock);

net/smc/smc_pnet.c

@@ -311,8 +311,9 @@ static struct smc_ib_device *smc_pnet_find_ib(char *ib_name)
 	list_for_each_entry(ibdev, &smc_ib_devices.list, list) {
 		if (!strncmp(ibdev->ibdev->name, ib_name,
 			     sizeof(ibdev->ibdev->name)) ||
-		    !strncmp(dev_name(ibdev->ibdev->dev.parent), ib_name,
-			     IB_DEVICE_NAME_MAX - 1)) {
+		    (ibdev->ibdev->dev.parent &&
+		     !strncmp(dev_name(ibdev->ibdev->dev.parent), ib_name,
+			     IB_DEVICE_NAME_MAX - 1))) {
 			goto out;
 		}
 	}