linux-kernel - [PATCH] staging: rtl8712: Fix possible buffer overflow in r8712_sitesurvey

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Message-Id: <20210301132648.420296-1-leegib@gmail.com>
Date:   Mon,  1 Mar 2021 13:26:48 +0000
From:   Lee Gibson <leegib@...il.com>
To:     gregkh@...uxfoundation.org
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Lee Gibson <leegib@...il.com>
Subject: [PATCH] staging: rtl8712: Fix possible buffer overflow in r8712_sitesurvey_cmd

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@...il.com>
---
 drivers/staging/rtl8712/rtl871x_cmd.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8712/rtl871x_cmd.c b/drivers/staging/rtl8712/rtl871x_cmd.c
index 18116469bd31..75716f59044d 100644
--- a/drivers/staging/rtl8712/rtl871x_cmd.c
+++ b/drivers/staging/rtl8712/rtl871x_cmd.c
@@ -192,8 +192,10 @@ u8 r8712_sitesurvey_cmd(struct _adapter *padapter,
 	psurveyPara->ss_ssidlen = 0;
 	memset(psurveyPara->ss_ssid, 0, IW_ESSID_MAX_SIZE + 1);
 	if (pssid && pssid->SsidLength) {
-		memcpy(psurveyPara->ss_ssid, pssid->Ssid, pssid->SsidLength);
-		psurveyPara->ss_ssidlen = cpu_to_le32(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);
-- 
2.25.1