[PATCH 3.16 025/366] mwifiex: pcie: tighten a check in mwifiex_pcie_process_event_ready()

[Ben Hutchings]

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 01eca2842874b9a85b7cd1e1b0e5b34a5d53a21f upstream.

If "evt_len" is 1 then we try to memcpy() negative 3 bytes and it would
cause memory corruption.

Fixes: d930faee141b ("mwifiex: add support for Marvell pcie8766 chipset")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/mwifiex/pcie.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/mwifiex/pcie.c
+++ b/drivers/net/wireless/mwifiex/pcie.c
@@ -1692,7 +1692,8 @@ static int mwifiex_pcie_process_event_re
 		skb_pull(skb_cmd, INTF_HEADER_LEN);
 		dev_dbg(adapter->dev, "info: Event length: %d\n", evt_len);
 
-		if ((evt_len > 0) && (evt_len  < MAX_EVENT_SIZE))
+		if (evt_len > MWIFIEX_EVENT_HEADER_LEN &&
+		    evt_len < MAX_EVENT_SIZE)
 			memcpy(adapter->event_body, skb_cmd->data +
 			       MWIFIEX_EVENT_HEADER_LEN, evt_len -
 			       MWIFIEX_EVENT_HEADER_LEN);