Return-path: Received: from zimbra.real-time.com ([63.170.91.9]:37203 "EHLO zimbra.real-time.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbbI2XLB (ORCPT ); Tue, 29 Sep 2015 19:11:01 -0400 Date: Wed, 30 Sep 2015 09:10:38 +1000 From: James Cameron To: PaX Team Cc: Amitkumar Karwar , Avinash Patil , Kalle Valo , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, re.emese@gmail.com, spender@grsecurity.net Subject: Re: question about potential integer truncation in mwifiex_set_wapi_ie and mwifiex_set_wps_ie Message-ID: <20150929231038.GG8613@us.netrek.org> (sfid-20150930_011105_814118_0251A296) References: <560AAC78.14106.6193CAA9@pageexec.freemail.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <560AAC78.14106.6193CAA9@pageexec.freemail.hu> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, Sep 29, 2015 at 05:21:28PM +0200, PaX Team wrote: > hi all, > > in drivers/net/wireless/mwifiex/sta_ioctl.c the following functions > > mwifiex_set_wpa_ie_helper > mwifiex_set_wapi_ie > mwifiex_set_wps_ie > > can truncate the incoming ie_len argument from u16 to u8 when it gets > stored in mwifiex_private.wpa_ie_len, mwifiex_private.wapi_ie_len and > mwifiex_private.wps_ie_len, respectively. based on some light code > reading it seems a length value of 256 is valid (IEEE_MAX_IE_SIZE and > MWIFIEX_MAX_VSIE_LEN seem to limit it) and thus would get truncated > to 0 when stored in those u8 fields. the question is whether this is > intentional or a bug somewhere. i agree, while there is a test to ensure ie_len is not greater than 256, there is a possibility that it will be exactly 256, which means 256 bytes will be given to memcpy but mwifiex_private.{wpa,wapi,wps}_ie_len will be zero. i suggest changing the lengths to u16. not tested. diff --git a/drivers/net/wireless/mwifiex/main.h b/drivers/net/wireless/mwifiex/main.h index fe12560..b66e9a7 100644 --- a/drivers/net/wireless/mwifiex/main.h +++ b/drivers/net/wireless/mwifiex/main.h @@ -512,14 +512,14 @@ struct mwifiex_private { struct mwifiex_wep_key wep_key[NUM_WEP_KEYS]; u16 wep_key_curr_index; u8 wpa_ie[256]; - u8 wpa_ie_len; + u16 wpa_ie_len; u8 wpa_is_gtk_set; struct host_cmd_ds_802_11_key_material aes_key; struct host_cmd_ds_802_11_key_material_v2 aes_key_v2; u8 wapi_ie[256]; - u8 wapi_ie_len; + u16 wapi_ie_len; u8 *wps_ie; - u8 wps_ie_len; + u16 wps_ie_len; u8 wmm_required; u8 wmm_enabled; u8 wmm_qosinfo; -- James Cameron http://quozl.linux.org.au/