[PATCH 4.14 08/46] net: set default network namespace in init_dummy_netdev()

Greg Kroah-Hartman
2019-02-04T11:04:42Z

From: Josh Elsasser <jelsasser@appneta.com>

[ Upstream commit 35edfdc77f683c8fd27d7732af06cf6489af60a5 ]

Assign a default net namespace to netdevs created by init_dummy_netdev().
Fixes a NULL pointer dereference caused by busy-polling a socket bound to
an iwlwifi wireless device, which bumps the per-net BUSYPOLLRXPACKETS stat
if napi_poll() received packets:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000190
IP: napi_busy_loop+0xd6/0x200
Call Trace:
sock_poll+0x5e/0x80
do_sys_poll+0x324/0x5a0
SyS_poll+0x6c/0xf0
do_syscall_64+0x6b/0x1f0
entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Fixes: 7db6b048da3b ("net: Commonize busy polling code to focus on napi_id instead of socket")
Signed-off-by: Josh Elsasser <jelsasser@appneta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/dev.c | 3 +++
1 file changed, 3 insertions(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7748,6 +7748,9 @@ int init_dummy_netdev(struct net_device
set_bit(__LINK_STATE_PRESENT, &dev->state);
set_bit(__LINK_STATE_START, &dev->state);

+ /* napi_busy_loop stats accounting wants this */
+ dev_net_set(dev, &init_net);
+
/* Note : We dont allocate pcpu_refcnt for dummy devices,
* because users of this 'device' dont need to change
* its refcount.