selftests/bpf: test_xsk: fix memory leak in testapp_stats_rx_dropped()

testapp_stats_rx_dropped() generates pkt_stream twice. The last
generated is released by pkt_stream_restore_default() at the end of the
test but we lose the pointer of the first pkt_stream.

Release the 'middle' pkt_stream when it's getting replaced to prevent
memory leaks.

Reviewed-by: Maciej Fijalkowski <[email protected]>
Signed-off-by: Bastien Curutchet (eBPF Foundation) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: bastien-curutchet

tools/testing/selftests/bpf/test_xsk.c

@@ -536,6 +536,13 @@ static void pkt_stream_receive_half(struct test_spec *test)
 	struct pkt_stream *pkt_stream = test->ifobj_tx->xsk->pkt_stream;
 	u32 i;
 
+	if (test->ifobj_rx->xsk->pkt_stream != test->rx_pkt_stream_default)
+		/* Packet stream has already been replaced so we have to release this one.
+		 * The newly created one will be freed by the restore_default() at the
+		 * end of the test
+		 */
+		pkt_stream_delete(test->ifobj_rx->xsk->pkt_stream);
+
 	test->ifobj_rx->xsk->pkt_stream = pkt_stream_generate(pkt_stream->nb_pkts,
 							      pkt_stream->pkts[0].len);
 	pkt_stream = test->ifobj_rx->xsk->pkt_stream;