[PATCH 3.16.y-ckt 146/180] ath9k_htc: check for underflow in ath9k_htc_rx_msg()

[Luis Henriques]

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Dan Carpenter <dan.carpenter at oracle.com>

commit 3a318426e09a9c9266fe6440842e11238f640a20 upstream.

We check for overflow here, but we don't check for underflow so it
causes a static checker warning.

Fixes: fb9987d0f748 ('ath9k_htc: Support for AR9271 chipset.')
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Kalle Valo <kvalo at codeaurora.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wireless/ath/ath9k/htc_hst.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index a0ff5b637054..93a86e24ff30 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -415,7 +415,7 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
 		return;
 	}
 
-	if (epid >= ENDPOINT_MAX) {
+	if (epid < 0 || epid >= ENDPOINT_MAX) {
 		if (pipe_id != USB_REG_IN_PIPE)
 			dev_kfree_skb_any(skb);
 		else