From 37ba3c350e64adcbdd483e81bf194c05d9573515 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Sat, 14 Apr 2018 17:06:44 +0200
Subject: [PATCH] HID: intel_ish-hid: Move header size check to inside the loop
Git-commit: 37ba3c350e64adcbdd483e81bf194c05d9573515
Patch-mainline: v4.17-rc5
References: jsc#SLE-5241

With the headersize check outside of the loop, the second time through
the loop the: "payload_len = recv_msg->hdr.size;" statement may deref
recv_msg while it is pointing outside of our input buffer.

Move the headersize check to inside the loop to fix this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/hid/intel-ish-hid/ishtp-hid-client.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/hid/intel-ish-hid/ishtp-hid-client.c b/drivers/hid/intel-ish-hid/ishtp-hid-client.c
index 157b44aacdff..6ce1856bb368 100644
--- a/drivers/hid/intel-ish-hid/ishtp-hid-client.c
+++ b/drivers/hid/intel-ish-hid/ishtp-hid-client.c
@@ -77,21 +77,21 @@ static void process_recv(struct ishtp_cl *hid_ishtp_cl, void *recv_buf,
 	struct ishtp_cl_data *client_data = hid_ishtp_cl->client_data;
 	int curr_hid_dev = client_data->cur_hid_dev;
 
-	if (data_len < sizeof(struct hostif_msg_hdr)) {
-		dev_err(&client_data->cl_device->dev,
-			"[hid-ish]: error, received %u which is less than data header %u\n",
-			(unsigned int)data_len,
-			(unsigned int)sizeof(struct hostif_msg_hdr));
-		++client_data->bad_recv_cnt;
-		ish_hw_reset(hid_ishtp_cl->dev);
-		return;
-	}
-
 	payload = recv_buf + sizeof(struct hostif_msg_hdr);
 	total_len = data_len;
 	cur_pos = 0;
 
 	do {
+		if (cur_pos + sizeof(struct hostif_msg) > total_len) {
+			dev_err(&client_data->cl_device->dev,
+				"[hid-ish]: error, received %u which is less than data header %u\n",
+				(unsigned int)data_len,
+				(unsigned int)sizeof(struct hostif_msg_hdr));
+			++client_data->bad_recv_cnt;
+			ish_hw_reset(hid_ishtp_cl->dev);
+			break;
+		}
+
 		recv_msg = (struct hostif_msg *)(recv_buf + cur_pos);
 		payload_len = recv_msg->hdr.size;
 
-- 
2.16.4