netdev - [PATCH net] net: bridge: fix a null pointer dereference in br

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Message-Id: <1496701584-26855-1-git-send-email-nikolay@cumulusnetworks.com>
Date:   Tue,  6 Jun 2017 01:26:24 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     netdev@...r.kernel.org
Cc:     roopa@...ulusnetworks.com, davem@...emloft.net,
        stephen@...workplumber.org, garsilva@...eddedor.com,
        bridge@...ts.linux-foundation.org,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

We might call br_afspec() with p == NULL which is a valid use case if
the action is on the bridge device itself, but the bridge tunnel code
dereferences the p pointer without checking, so check if p is null
first.

Reported-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
---
 net/bridge/br_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1e63ec466d7c..3bcda556971e 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -595,7 +595,7 @@ static int br_afspec(struct net_bridge *br,
 		err = 0;
 		switch (nla_type(attr)) {
 		case IFLA_BRIDGE_VLAN_TUNNEL_INFO:
-			if (!(p->flags & BR_VLAN_TUNNEL))
+			if (!p || !(p->flags & BR_VLAN_TUNNEL))
 				return -EINVAL;
 			err = br_parse_vlan_tunnel_info(attr, &tinfo_curr);
 			if (err)
-- 
2.1.4