From 08bb4da90150e2a225f35e0f642cdc463958d696 Mon Sep 17 00:00:00 2001
From: Alain Michaud <alainm@chromium.org>
Date: Tue, 3 Mar 2020 15:55:34 +0000
Subject: [PATCH] Bluetooth: guard against controllers sending zero'd events
Git-commit: 08bb4da90150e2a225f35e0f642cdc463958d696
Patch-mainline: v5.7-rc1
References: git-fixes

Some controllers have been observed to send zero'd events under some
conditions.  This change guards against this condition as well as adding
a trace to facilitate diagnosability of this condition.

Signed-off-by: Alain Michaud <alainm@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/bluetooth/hci_event.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 591e7477e925..a40ed31f6eb8 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -5868,6 +5868,11 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 	u8 status = 0, event = hdr->evt, req_evt = 0;
 	u16 opcode = HCI_OP_NOP;
 
+	if (!event) {
+		bt_dev_warn(hdev, "Received unexpected HCI Event 00000000");
+		goto done;
+	}
+
 	if (hdev->sent_cmd && bt_cb(hdev->sent_cmd)->hci.req_event == event) {
 		struct hci_command_hdr *cmd_hdr = (void *) hdev->sent_cmd->data;
 		opcode = __le16_to_cpu(cmd_hdr->opcode);
@@ -6079,6 +6084,7 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 		req_complete_skb(hdev, status, opcode, orig_skb);
 	}
 
+done:
 	kfree_skb(orig_skb);
 	kfree_skb(skb);
 	hdev->stat.evt_rx++;
-- 
2.16.4