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From:   gregkh@linuxfoundation.org
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Lee Gibson <leegib@gmail.com>
Subject: [PATCH 4.19 094/120] staging: rtl8712: Fix possible buffer overflow in r8712_sitesurvey_cmd
Date:   Mon, 15 Mar 2021 14:57:25 +0100
Message-Id: <20210315135723.056930586@linuxfoundation.org>
In-Reply-To: <20210315135720.002213995@linuxfoundation.org>
References: <20210315135720.002213995@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Lee Gibson <leegib@gmail.com>

commit b93c1e3981af19527beee1c10a2bef67a228c48c upstream.

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

--- a/drivers/staging/rtl8712/rtl871x_cmd.c
+++ b/drivers/staging/rtl8712/rtl871x_cmd.c
@@ -242,8 +242,10 @@ u8 r8712_sitesurvey_cmd(struct _adapter
 	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);
+		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);