From b93c1e3981af19527beee1c10a2bef67a228c48c Mon Sep 17 00:00:00 2001
From: Lee Gibson <leegib@gmail.com>
Date: Mon, 1 Mar 2021 13:26:48 +0000
Subject: [PATCH] staging: rtl8712: Fix possible buffer overflow in r8712_sitesurvey_cmd
Git-commit: b93c1e3981af19527beee1c10a2bef67a228c48c
Patch-mainline: v5.12-rc3
References: git-fixes

Function r8712_sitesurvey_cmd 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@gmail.com>
Link: https://lore.kernel.org/r/20210301132648.420296-1-leegib@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/rtl8712/rtl871x_cmd.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/staging/rtl8712/rtl871x_cmd.c
+++ b/drivers/staging/rtl8712/rtl871x_cmd.c
@@ -196,9 +196,11 @@ u8 r8712_sitesurvey_cmd(struct _adapter
 	psurveyPara->passive_mode = cpu_to_le32(pmlmepriv->passive_mode);
 	psurveyPara->ss_ssidlen = 0;
 	memset(psurveyPara->ss_ssid, 0, IW_ESSID_MAX_SIZE + 1);
-	if ((pssid != NULL) && (pssid->SsidLength)) {
-		memcpy(psurveyPara->ss_ssid, pssid->Ssid, pssid->SsidLength);
-		psurveyPara->ss_ssidlen = cpu_to_le32(pssid->SsidLength);
+	if (pssid && pssid->SsidLength) {
+		int len = min_t(int, pssid->SsidLength, IW_ESSID_MAX_SIZE);
+
+		memcpy(psurveyPara->ss_ssid, pssid->Ssid, len);
+		psurveyPara->ss_ssidlen = cpu_to_le32(len);
 	}
 	set_fwstate(pmlmepriv, _FW_UNDER_SURVEY);
 	r8712_enqueue_cmd(pcmdpriv, ph2c);