[PATCH 5.7 282/393] s390/qeth: dont process empty bridge port events

[Greg Kroah-Hartman]

From: Julian Wiedmann <jwi@xxxxxxxxxxxxx>

[ Upstream commit 02472e28b9a45471c6d8729ff2c7422baa9be46a ]

Discard events that don't contain any entries. This shouldn't happen,
but subsequent code relies on being able to use entry 0. So better
be safe than accessing garbage.

Fixes: b4d72c08b358 ("qeth: bridgeport support - basic control")
Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
Reviewed-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/s390/net/qeth_l2_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 0bd5b09e7a223..37740cc7a44aa 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -1071,6 +1071,10 @@ static void qeth_bridge_state_change(struct qeth_card *card,
 	int extrasize;
 
 	QETH_CARD_TEXT(card, 2, "brstchng");
+	if (qports->num_entries == 0) {
+		QETH_CARD_TEXT(card, 2, "BPempty");
+		return;
+	}
 	if (qports->entry_length != sizeof(struct qeth_sbp_port_entry)) {
 		QETH_CARD_TEXT_(card, 2, "BPsz%04x", qports->entry_length);
 		return;
-- 
2.25.1