[PATCH 5.13 529/800] xfrm: Fix xfrm offload fallback fail case

[Greg Kroah-Hartman]

From: Ayush Sawal <ayush.sawal@xxxxxxxxxxx>

[ Upstream commit dd72fadf2186fc8a6018f97fe72f4d5ca05df440 ]

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: bdfd2d1fa79a ("bonding/xfrm: use real_dev instead of slave_dev")
Signed-off-by: Ayush Sawal <ayush.sawal@xxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/xfrm/xfrm_device.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
index 6d6917b68856..e843b0d9e2a6 100644
--- a/net/xfrm/xfrm_device.c
+++ b/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)
-- 
2.30.2