[PATCH] net: bridge: check for a null p->dev before dereferencing it

[Colin King]

From: Colin Ian King <colin.k...@canonical.com>

A recent change added a null check on p->dev after p->dev was being
dereferenced by the ns_capable check on p->dev.  Fix this by performing
the p->dev sanity check before it is dereferenced.

Detected by CoverityScan, CID#751490 ("Dereference before null check")

Fixes: a5f3ea54f3cc ("net: bridge: add support for raw sysfs port options")
Signed-off-by: Colin Ian King <colin.k...@canonical.com>
---
 net/bridge/br_sysfs_if.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 7c87a2fe5248..aab8aa17cccf 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -314,15 +314,15 @@ static ssize_t brport_store(struct kobject *kobj,
        unsigned long val;
        char *endp;
 
+       if (!p->dev || !p->br)
+               return -EINVAL;
+
        if (!ns_capable(dev_net(p->dev)->user_ns, CAP_NET_ADMIN))
                return -EPERM;
 
        if (!rtnl_trylock())
                return restart_syscall();
 
-       if (!p->dev || !p->br)
-               goto out_unlock;
-
        if (brport_attr->store_raw) {
                char *buf_copy;
 
-- 
2.19.1