xfrm: policy: fix null dereference

xfrm: policy: fix null dereference

Julian Wiedmann says:
> +     if (!xfrm_pol_hold_rcu(ret))

Coverity spotted that ^^^ needs a s/ret/pol fix-up:

> CID 1599386:  Null pointer dereferences  (FORWARD_NULL)
> Passing null pointer "ret" to "xfrm_pol_hold_rcu", which dereferences it.

Ditch the bogus 'ret' variable.

Fixes: 563d5ca93e88 ("xfrm: switch migrate to xfrm_policy_lookup_bytype")
Reported-by: Julian Wiedmann <jwiedmann.dev@gmail.com>
Closes: https://lore.kernel.org/netdev/06dc2499-c095-4bd4-aee3-a1d0e3ec87c4@gmail.com/
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>