Free sessionid in clean_work and remove redundant setting of strings to NULL since the whole work struct is zeroed.
diff --git a/cgminer.c b/cgminer.c
index a9f34d5..47496df 100644
--- a/cgminer.c
+++ b/cgminer.c
@@ -1380,10 +1380,7 @@ void clean_work(struct work *work)
free(work->nonce2);
free(work->ntime);
free(work->gbt_coinbase);
- work->job_id = NULL;
- work->nonce2 = NULL;
- work->ntime = NULL;
- work->gbt_coinbase = NULL;
+ free(work->sessionid);
memset(work, 0, sizeof(struct work));
}