[PATCH net 0/2] net/smc: fixes 2021-11-24

Patch 1 from DaXing fixes a possible loop in smc_listen().
Patch 2 prevents a NULL pointer dereferencing while iterating
over the lower network devices.

Guo DaXing (1):
  net/smc: Fix loop in smc_listen

Karsten Graul (1):
  net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()

 net/smc/af_smc.c   |  4 +++-
 net/smc/smc_core.c | 35 ++++++++++++++++++-----------------
 2 files changed, 21 insertions(+), 18 deletions(-)

-- 
2.32.0

From: Guo DaXing <redacted>

The kernel_listen function in smc_listen will fail when all the available
ports are occupied.  At this point smc->clcsock->sk->sk_data_ready has
been changed to smc_clcsock_data_ready.  When we call smc_listen again,
now both smc->clcsock->sk->sk_data_ready and smc->clcsk_data_ready point
to the smc_clcsock_data_ready function.

The smc_clcsock_data_ready() function calls lsmc->clcsk_data_ready which
now points to itself resulting in an infinite loop.

This patch restores smc->clcsock->sk->sk_data_ready with the old value.

Fixes: a60a2b1e0af1 ("net/smc: reduce active tcp_listen workers")
Signed-off-by: Guo DaXing <redacted>
Acked-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Karsten Graul <redacted>
---
 net/smc/af_smc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index b61c802e3bf3..53a617cbbec4 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c

@@ -2134,8 +2134,10 @@ static int smc_listen(struct socket *sock, int backlog)
 	smc->clcsock->sk->sk_user_data =
 		(void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY);
 	rc = kernel_listen(smc->clcsock, backlog);
-	if (rc)
+	if (rc) {
+		smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
 		goto out;
+	}
 	sk->sk_max_ack_backlog = backlog;
 	sk->sk_ack_backlog = 0;
 	sk->sk_state = SMC_LISTEN;

-- 
2.32.0

Coverity reports a possible NULL dereferencing problem:

in smc_vlan_by_tcpsk():
6. returned_null: netdev_lower_get_next returns NULL (checked 29 out of 30 times).
7. var_assigned: Assigning: ndev = NULL return value from netdev_lower_get_next.
1623                ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);
CID 1468509 (#1 of 1): Dereference null return value (NULL_RETURNS)
8. dereference: Dereferencing a pointer that might be NULL ndev when calling is_vlan_dev.
1624                if (is_vlan_dev(ndev)) {

Remove the manual implementation and use netdev_walk_all_lower_dev() to
iterate over the lower devices. While on it remove an obsolete function
parameter comment.

Fixes: cb9d43f67754 ("net/smc: determine vlan_id of stacked net_device")
Suggested-by: Julian Wiedmann <redacted>
Signed-off-by: Karsten Graul <redacted>
---
 net/smc/smc_core.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 25ebd30feecd..bb52c8b5f148 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c

@@ -1672,14 +1672,26 @@ static void smc_link_down_work(struct work_struct *work)
 	mutex_unlock(&lgr->llc_conf_mutex);
 }
 
-/* Determine vlan of internal TCP socket.
- * @vlan_id: address to store the determined vlan id into
- */
+static int smc_vlan_by_tcpsk_walk(struct net_device *lower_dev,
+				  struct netdev_nested_priv *priv)
+{
+	unsigned short *vlan_id = (unsigned short *)priv->data;
+
+	if (is_vlan_dev(lower_dev)) {
+		*vlan_id = vlan_dev_vlan_id(lower_dev);
+		return 1;
+	}
+
+	return 0;
+}
+
+/* Determine vlan of internal TCP socket. */
 int smc_vlan_by_tcpsk(struct socket *clcsock, struct smc_init_info *ini)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
+	struct netdev_nested_priv priv;
 	struct net_device *ndev;
-	int i, nest_lvl, rc = 0;
+	int rc = 0;
 
 	ini->vlan_id = 0;
 	if (!dst) {

@@ -1697,20 +1709,9 @@ int smc_vlan_by_tcpsk(struct socket *clcsock, struct smc_init_info *ini)
 		goto out_rel;
 	}
 
+	priv.data = (void *)&ini->vlan_id;
 	rtnl_lock();
-	nest_lvl = ndev->lower_level;
-	for (i = 0; i < nest_lvl; i++) {
-		struct list_head *lower = &ndev->adj_list.lower;
-
-		if (list_empty(lower))
-			break;
-		lower = lower->next;
-		ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);
-		if (is_vlan_dev(ndev)) {
-			ini->vlan_id = vlan_dev_vlan_id(ndev);
-			break;
-		}
-	}
+	netdev_walk_all_lower_dev(ndev, smc_vlan_by_tcpsk_walk, &priv);
 	rtnl_unlock();
 
 out_rel:

-- 
2.32.0

Hello:

This series was applied to netdev/net.git (master)
by Jakub Kicinski [off-list ref]:

On Wed, 24 Nov 2021 13:32:36 +0100 you wrote:

Patch 1 from DaXing fixes a possible loop in smc_listen().
Patch 2 prevents a NULL pointer dereferencing while iterating
over the lower network devices.

Guo DaXing (1):
  net/smc: Fix loop in smc_listen

[...]

Here is the summary with links:
  - [net,1/2] net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()
    https://git.kernel.org/netdev/net/c/587acad41f1b
  - [net,2/2] net/smc: Fix loop in smc_listen
    https://git.kernel.org/netdev/net/c/9ebb0c4b27a6

You are awesome, thank you!
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