From 74b6b20df8cfe90ada777d621b54c32e69e27cd7 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 5 Mar 2021 11:58:03 +0300
Subject: [PATCH] staging: rtl8188eu: prevent ->ssid overflow in rtw_wx_set_scan()
Git-commit: 74b6b20df8cfe90ada777d621b54c32e69e27cd7
Patch-mainline: v5.12-rc3
References: CVE-2021-28660 bsc#1183593

This code has a check to prevent read overflow but it needs another
check to prevent writing beyond the end of the ->ssid[] array.

Fixes: a2c60d42d97c ("staging: r8188eu: Add files for new driver - part 16")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YEHymwsnHewzoam7@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/rtl8188eu/os_dep/ioctl_linux.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/staging/rtl8188eu/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8188eu/os_dep/ioctl_linux.c
@@ -1169,9 +1169,11 @@ static int rtw_wx_set_scan(struct net_de
 						break;
 					}
 					sec_len = *(pos++); len -= 1;
-					if (sec_len > 0 && sec_len <= len) {
+					if (sec_len > 0 &&
+					    sec_len <= len &&
+					    sec_len <= 32) {
 						ssid[ssid_index].SsidLength = sec_len;
-						memcpy(ssid[ssid_index].Ssid, pos, ssid[ssid_index].SsidLength);
+						memcpy(ssid[ssid_index].Ssid, pos, sec_len);
 						ssid_index++;
 					}
 					pos += sec_len;