hash: fix use after free in Toeplitz hash

This patch fixes use after free in thash library, reported by ASAN.

Bugzilla ID: 868
Fixes: 28ebff1 ("hash: add predictable RSS")
Cc: stable@dpdk.org

Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>

lib/hash/rte_thash.c

@@ -468,10 +468,10 @@ insert_before(struct rte_thash_ctx *ctx,
 			return ret;
 		}
 	} else if ((next_ent != NULL) && (end > next_ent->offset)) {
-		rte_free(ent);
 		RTE_LOG(ERR, HASH,
 			"Can't add helper %s due to conflict with existing"
 			" helper %s\n", ent->name, next_ent->name);
+		rte_free(ent);
 		return -ENOSPC;
 	}
 	attach_lfsr(ent, cur_ent->lfsr);
@@ -517,10 +517,10 @@ insert_after(struct rte_thash_ctx *ctx,
 	int ret;
 
 	if ((next_ent != NULL) && (end > next_ent->offset)) {
-		rte_free(ent);
 		RTE_LOG(ERR, HASH,
 			"Can't add helper %s due to conflict with existing"
 			" helper %s\n", ent->name, next_ent->name);
+		rte_free(ent);
 		return -EEXIST;
 	}