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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alain Michaud <alainm@chromium.org>,
        Marcel Holtmann <marcel@holtmann.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 39/85] Bluetooth: guard against controllers sending zerod events
Date:   Tue, 29 Sep 2020 13:00:06 +0200
Message-Id: <20200929105930.180096664@linuxfoundation.org>
In-Reply-To: <20200929105928.198942536@linuxfoundation.org>
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From: Alain Michaud <alainm@chromium.org>

[ Upstream commit 08bb4da90150e2a225f35e0f642cdc463958d696 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 16cf5633eae3e..04c77747a768d 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -5230,6 +5230,11 @@ 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);
@@ -5441,6 +5446,7 @@ 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++;
-- 
2.25.1