xfrm: Fix xfrm offload fallback fail case

stable inclusion
from stable-5.10.50
commit 78e6587585d878aefc7ad31464b23bda3b3cacf0
bugzilla: 174522 https://gitee.com/openeuler/kernel/issues/I4DNFY

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=78e6587585d878aefc7ad31464b23bda3b3cacf0

--------------------------------

[ Upstream commit dd72fadf ]

In case of xfrm offload, if xdo_dev_state_add() of driver returns
-EOPNOTSUPP, xfrm offload fallback is failed.
In xfrm state_add() both xso->dev and xso->real_dev are initialized to
dev and when err(-EOPNOTSUPP) is returned only xso->dev is set to null.

So in this scenario the condition in func validate_xmit_xfrm(),
if ((x->xso.dev != dev) && (x->xso.real_dev == dev))
                return skb;
returns true, due to which skb is returned without calling esp_xmit()
below which has fallback code. Hence the CRYPTO_FALLBACK is failing.

So fixing this with by keeping x->xso.real_dev as NULL when err is
returned in func xfrm_dev_state_add().

Fixes: bdfd2d1f ("bonding/xfrm: use real_dev instead of slave_dev")
Signed-off-by: NAyush Sawal <ayush.sawal@chelsio.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/xfrm/xfrm_device.c

@@ -268,6 +268,7 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
 		xso->num_exthdrs = 0;
 		xso->flags = 0;
 		xso->dev = NULL;
+		xso->real_dev = NULL;
 		dev_put(dev);
 
 		if (err != -EOPNOTSUPP)