env/dpdk: add security checks to spdk_env_get_socket_id()

The underlying DPDK function we use reads an array
at the provided index without checking for any out
of bounds access. The array is RTE_MAX_LCORE elements
long, so always manually check against that to keep
our APIs safe.

This fixes potential crashes with lcore == SPDK_ENV_LCORE_ID_ANY

Change-Id: I3081b888275fbecba8ab95feb20d2074341e2fc7
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/425042
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

lib/env_dpdk/threads.c

@@ -84,6 +84,10 @@ spdk_env_get_next_core(uint32_t prev_core)
 uint32_t
 spdk_env_get_socket_id(uint32_t core)
 {
+	if (core >= RTE_MAX_LCORE) {
+		return SPDK_ENV_SOCKET_ID_ANY;
+	}
+
 	return rte_lcore_to_socket_id(core);
 }