[PATCH AUTOSEL 5.4 41/46] qtnfmac: Fix possible buffer overflow in qtnf_event_handle_external_auth

[Sasha Levin]

From: Lee Gibson <leegib@xxxxxxxxx>

[ Upstream commit 130f634da1af649205f4a3dd86cbe5c126b57914 ]

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 <leegib@xxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210419145842.345787-1-leegib@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 7846383c8828..3f24dbdae8d0 100644
--- a/drivers/net/wireless/quantenna/qtnfmac/event.c
+++ b/drivers/net/wireless/quantenna/qtnfmac/event.c
@@ -599,8 +599,10 @@ 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);
-- 
2.30.2