[PATCH v2] qtnfmac: Fix possible buffer overflow in qtnf_event_handle_external_auth

[Lee Gibson]

Function qtnf_event_handle_external_auth calls memcpy without
checking the length.
A user could control that length and trigger a buffer overflow.
Fix by checking the length is within the maximum allowed size.

Signed-off-by: Lee Gibson <lee...@gmail.com>
---

v2: use clamp_val() instead of min_t()

 drivers/net/wireless/quantenna/qtnfmac/event.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/quantenna/qtnfmac/event.c 
b/drivers/net/wireless/quantenna/qtnfmac/event.c
index c775c177933b..8dc80574d08d 100644
--- a/drivers/net/wireless/quantenna/qtnfmac/event.c
+++ b/drivers/net/wireless/quantenna/qtnfmac/event.c
@@ -570,8 +570,10 @@ qtnf_event_handle_external_auth(struct qtnf_vif *vif,
                return 0;
 
        if (ev->ssid_len) {
-               memcpy(auth.ssid.ssid, ev->ssid, ev->ssid_len);
-               auth.ssid.ssid_len = ev->ssid_len;
+               int len = clamp_val(ev->ssid_len, 0, IEEE80211_MAX_SSID_LEN);
+
+               memcpy(auth.ssid.ssid, ev->ssid, len);
+               auth.ssid.ssid_len = len;
        }
 
        auth.key_mgmt_suite = le32_to_cpu(ev->akm_suite);
-- 
2.25.1