staging: rtl8723bs: os_dep: Replace sprintf with scnprintf

The use of sprintf with format string here means that there is a risk
that the writes will go out of bounds, replace it with scnprintf.

In one block of the translate_scan function sprintf is only called once
(it's not being used to concatenate strings) so there is no need to keep
the pointer "p", remove it.
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Candy Febriyanto <cfebriyanto@gmail.com>
Link: https://lore.kernel.org/r/d76c5f1db8dbf02ac0ab954b0971ce24e5a8b9bd.1614610197.git.cfebriyanto@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/os_dep/ioctl_linux.c

@@ -240,9 +240,10 @@ static char *translate_scan(struct adapter *padapter,
 			return start;
 		if (wpa_len > 0) {
 			p = buf;
-			p += sprintf(p, "wpa_ie =");
+			p += scnprintf(p, (MAX_WPA_IE_LEN * 2) - (p - buf), "wpa_ie =");
 			for (i = 0; i < wpa_len; i++)
-				p += sprintf(p, "%02x", wpa_ie[i]);
+				p += scnprintf(p, (MAX_WPA_IE_LEN * 2) - (p - buf),
+						"%02x", wpa_ie[i]);
 
 			if (wpa_len > 100) {
 				printk("-----------------Len %d----------------\n", wpa_len);
@@ -265,9 +266,10 @@ static char *translate_scan(struct adapter *padapter,
 		if (rsn_len > 0) {
 			p = buf;
 			memset(buf, 0, MAX_WPA_IE_LEN*2);
-			p += sprintf(p, "rsn_ie =");
+			p += scnprintf(p, (MAX_WPA_IE_LEN * 2) - (p - buf), "rsn_ie =");
 			for (i = 0; i < rsn_len; i++)
-				p += sprintf(p, "%02x", rsn_ie[i]);
+				p += scnprintf(p, (MAX_WPA_IE_LEN * 2) - (p - buf),
+						"%02x", rsn_ie[i]);
 			memset(&iwe, 0, sizeof(iwe));
 			iwe.cmd = IWEVCUSTOM;
 			iwe.u.data.length = strlen(buf);
@@ -365,17 +367,16 @@ static char *translate_scan(struct adapter *padapter,
 
 	{
 		u8 *buf;
-		u8 *p, *pos;
+		u8 *pos;
 
 		buf = kzalloc(MAX_WPA_IE_LEN, GFP_ATOMIC);
 		if (!buf)
 			goto exit;
-		p = buf;
+
 		pos = pnetwork->network.Reserved;
-		p += sprintf(p, "fm =%02X%02X", pos[1], pos[0]);
 		memset(&iwe, 0, sizeof(iwe));
 		iwe.cmd = IWEVCUSTOM;
-		iwe.u.data.length = strlen(buf);
+		iwe.u.data.length = scnprintf(buf, MAX_WPA_IE_LEN, "fm =%02X%02X", pos[1], pos[0]);
 		start = iwe_stream_add_point(info, start, stop, &iwe, buf);
 		kfree(buf);
 	}
@@ -5082,8 +5083,7 @@ static int rtw_ioctl_wext_private(struct net_device *dev, union iwreq_data *wrq_
 		case IW_PRIV_TYPE_BYTE:
 			/* Display args */
 			for (j = 0; j < n; j++) {
-				sprintf(str, "%d  ", extra[j]);
-				len = strlen(str);
+				len = scnprintf(str, sizeof(str), "%d  ", extra[j]);
 				output_len = strlen(output);
 				if ((output_len + len + 1) > 4096) {
 					err = -E2BIG;
@@ -5096,8 +5096,7 @@ static int rtw_ioctl_wext_private(struct net_device *dev, union iwreq_data *wrq_
 		case IW_PRIV_TYPE_INT:
 			/* Display args */
 			for (j = 0; j < n; j++) {
-				sprintf(str, "%d  ", ((__s32 *)extra)[j]);
-				len = strlen(str);
+				len = scnprintf(str, sizeof(str), "%d  ", ((__s32 *)extra)[j]);
 				output_len = strlen(output);
 				if ((output_len + len + 1) > 4096) {
 					err = -E2BIG;

drivers/staging/rtl8723bs/os_dep/mlme_linux.c

@@ -159,15 +159,15 @@ void rtw_report_sec_ie(struct adapter *adapter, u8 authmode, u8 *sec_ie)
 		}
 		p = buff;
 
-		p += sprintf(p, "ASSOCINFO(ReqIEs =");
+		p += scnprintf(p, IW_CUSTOM_MAX - (p - buff), "ASSOCINFO(ReqIEs =");
 
 		len = sec_ie[1] + 2;
 		len = (len < IW_CUSTOM_MAX) ? len : IW_CUSTOM_MAX;
 
 		for (i = 0; i < len; i++)
-			p += sprintf(p, "%02x", sec_ie[i]);
+			p += scnprintf(p, IW_CUSTOM_MAX - (p - buff), "%02x", sec_ie[i]);
 
-		p += sprintf(p, ")");
+		p += scnprintf(p, IW_CUSTOM_MAX - (p - buff), ")");
 
 		memset(&wrqu, 0, sizeof(wrqu));