linux-kernel - [PATCH net-next v2] net: vlan: Avoid using BUG() in vlan_proto

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Message-Id: <20200925002746.79571-1-f.fainelli@gmail.com>
Date:   Thu, 24 Sep 2020 17:27:44 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     olteanv@...il.com, vladimir.oltean@....com,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Taehee Yoo <ap420073@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net-next v2] net: vlan: Avoid using BUG() in vlan_proto_idx()

While we should always make sure that we specify a valid VLAN protocol
to vlan_proto_idx(), killing the machine when an invalid value is
specified is too harsh and not helpful for debugging. All callers are
capable of dealing with an error returned by vlan_proto_idx() so check
the index value and propagate it accordingly.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
Changes in v2:
- changed signature to return int
- changed message to use ntohs()
- renamed an index variable to 'pidx' instead of 'pdix'

 net/8021q/vlan.c |  3 +++
 net/8021q/vlan.h | 19 +++++++++++++------
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index d4bcfd8f95bf..6c08de1116c1 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -57,6 +57,9 @@ static int vlan_group_prealloc_vid(struct vlan_group *vg,
 	ASSERT_RTNL();
 
 	pidx  = vlan_proto_idx(vlan_proto);
+	if (pidx < 0)
+		return -EINVAL;
+
 	vidx  = vlan_id / VLAN_GROUP_ARRAY_PART_LEN;
 	array = vg->vlan_devices_arrays[pidx][vidx];
 	if (array != NULL)
diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index bb7ec1a3915d..953405362795 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h
@@ -36,7 +36,7 @@ struct vlan_info {
 	struct rcu_head		rcu;
 };
 
-static inline unsigned int vlan_proto_idx(__be16 proto)
+static inline int vlan_proto_idx(__be16 proto)
 {
 	switch (proto) {
 	case htons(ETH_P_8021Q):
@@ -44,8 +44,8 @@ static inline unsigned int vlan_proto_idx(__be16 proto)
 	case htons(ETH_P_8021AD):
 		return VLAN_PROTO_8021AD;
 	default:
-		BUG();
-		return 0;
+		WARN(1, "invalid VLAN protocol: 0x%04x\n", ntohs(proto));
+		return -EINVAL;
 	}
 }
 
@@ -64,17 +64,24 @@ static inline struct net_device *vlan_group_get_device(struct vlan_group *vg,
 						       __be16 vlan_proto,
 						       u16 vlan_id)
 {
-	return __vlan_group_get_device(vg, vlan_proto_idx(vlan_proto), vlan_id);
+	int pidx = vlan_proto_idx(vlan_proto);
+
+	if (pidx < 0)
+		return NULL;
+
+	return __vlan_group_get_device(vg, pidx, vlan_id);
 }
 
 static inline void vlan_group_set_device(struct vlan_group *vg,
 					 __be16 vlan_proto, u16 vlan_id,
 					 struct net_device *dev)
 {
+	int pidx = vlan_proto_idx(vlan_proto);
 	struct net_device **array;
-	if (!vg)
+
+	if (!vg || pidx < 0)
 		return;
-	array = vg->vlan_devices_arrays[vlan_proto_idx(vlan_proto)]
+	array = vg->vlan_devices_arrays[pidx]
 				       [vlan_id / VLAN_GROUP_ARRAY_PART_LEN];
 	array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] = dev;
 }
-- 
2.25.1