af_key: pfkey_dump needs parameter validation

In pfkey_dump() dplen and splen can both be specified to access the
xfrm_address_t structure out of bounds in__xfrm_state_filter_match()
when it calls addr_match() with the indexes.  Return EINVAL if either
are out of range.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
