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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, Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH 4.19 092/120] staging: rtl8188eu: fix potential memory corruption in rtw_check_beacon_data()
Date:   Mon, 15 Mar 2021 14:57:23 +0100
Message-Id: <20210315135722.989691938@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: Dan Carpenter <dan.carpenter@oracle.com>

commit d4ac640322b06095128a5c45ba4a1e80929fe7f3 upstream.

The "ie_len" is a value in the 1-255 range that comes from the user.  We
have to cap it to ensure that it's not too large or it could lead to
memory corruption.

Fixes: 9a7fe54ddc3a ("staging: r8188eu: Add source files for new driver - part 1")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YEHyQCrFZKTXyT7J@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/rtl8188eu/core/rtw_ap.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/staging/rtl8188eu/core/rtw_ap.c
+++ b/drivers/staging/rtl8188eu/core/rtw_ap.c
@@ -794,6 +794,7 @@ int rtw_check_beacon_data(struct adapter
 	/* SSID */
 	p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, _SSID_IE_, &ie_len, (pbss_network->ie_length - _BEACON_IE_OFFSET_));
 	if (p && ie_len > 0) {
+		ie_len = min_t(int, ie_len, sizeof(pbss_network->Ssid.Ssid));
 		memset(&pbss_network->Ssid, 0, sizeof(struct ndis_802_11_ssid));
 		memcpy(pbss_network->Ssid.Ssid, (p + 2), ie_len);
 		pbss_network->Ssid.SsidLength = ie_len;
@@ -812,6 +813,7 @@ int rtw_check_beacon_data(struct adapter
 	/*  get supported rates */
 	p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, _SUPPORTEDRATES_IE_, &ie_len, (pbss_network->ie_length - _BEACON_IE_OFFSET_));
 	if (p) {
+		ie_len = min_t(int, ie_len, NDIS_802_11_LENGTH_RATES_EX);
 		memcpy(supportRate, p + 2, ie_len);
 		supportRateNum = ie_len;
 	}
@@ -819,6 +821,8 @@ int rtw_check_beacon_data(struct adapter
 	/* get ext_supported rates */
 	p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, _EXT_SUPPORTEDRATES_IE_, &ie_len, pbss_network->ie_length - _BEACON_IE_OFFSET_);
 	if (p) {
+		ie_len = min_t(int, ie_len,
+			       NDIS_802_11_LENGTH_RATES_EX - supportRateNum);
 		memcpy(supportRate + supportRateNum, p + 2, ie_len);
 		supportRateNum += ie_len;
 	}
@@ -932,6 +936,7 @@ int rtw_check_beacon_data(struct adapter
 
 		pht_cap->mcs.rx_mask[0] = 0xff;
 		pht_cap->mcs.rx_mask[1] = 0x0;
+		ie_len = min_t(int, ie_len, sizeof(pmlmepriv->htpriv.ht_cap));
 		memcpy(&pmlmepriv->htpriv.ht_cap, p+2, ie_len);
 	}