Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752356AbdF3SEo (ORCPT ); Fri, 30 Jun 2017 14:04:44 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:34145 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752162AbdF3SEn (ORCPT ); Fri, 30 Jun 2017 14:04:43 -0400 Date: Fri, 30 Jun 2017 11:04:39 -0700 From: Dmitry Torokhov To: Brian Norris Cc: Ganapathi Bhat , Nishant Sarmukadam , Kalle Valo , linux-kernel@vger.kernel.org, Amitkumar Karwar , linux-wireless@vger.kernel.org, stable@vger.kernel.org, Avinash Patil , Xinming Hu Subject: Re: [PATCH] mwifiex: correct channel stat buffer overflows Message-ID: <20170630180439.GA40906@dtor-ws> References: <20170630012354.98931-1-briannorris@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170630012354.98931-1-briannorris@chromium.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3582 Lines: 81 On Thu, Jun 29, 2017 at 06:23:54PM -0700, Brian Norris wrote: > mwifiex records information about various channels as it receives scan > information. It does this by appending to a buffer that was sized > to the max number of supported channels on any band, but there are > numerous problems: > > (a) scans can return info from more than one band (e.g., both 2.4 and 5 > GHz), so the determined "max" is not large enough > (b) some firmware appears to return multiple results for a given > channel, so the max *really* isn't large enough > (c) there is no bounds checking when stashing these stats, so problems > (a) and (b) can easily lead to buffer overflows > > Let's patch this by setting a slightly-more-correct max (that accounts > for a combination of both 2.4G and 5G bands) and adding a bounds check > when writing to our statistics buffer. > > Due to problem (b), we still might not properly report all known survey > information (e.g., with "iw survey dump"), since duplicate results > (or otherwise "larger than expected" results) will cause some > truncation. But that's a problem for a future bugfix. > > (And because of this known deficiency, only log the excess at the WARN > level, since that isn't visible by default in this driver and would > otherwise be a bit too noisy.) > > Fixes: bf35443314ac ("mwifiex: channel statistics support for mwifiex") > Cc: > Cc: Avinash Patil > Cc: Xinming Hu > Signed-off-by: Brian Norris > --- > I've got a ton of other patches still queued up locally, and I hope to send > them soon. But I realized this one is a nasty bug (with a trivial fix), so it's > probably best to get this out the door quickly. This does make sense to me. Reviewed-by: Dmitry Torokhov > > drivers/net/wireless/marvell/mwifiex/cfg80211.c | 2 +- > drivers/net/wireless/marvell/mwifiex/scan.c | 6 ++++++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c b/drivers/net/wireless/marvell/mwifiex/cfg80211.c > index a850ec0054e2..82f4e796ed39 100644 > --- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c > +++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c > @@ -4219,7 +4219,7 @@ int mwifiex_init_channel_scan_gap(struct mwifiex_adapter *adapter) > if (adapter->config_bands & BAND_A) > n_channels_a = mwifiex_band_5ghz.n_channels; > > - adapter->num_in_chan_stats = max_t(u32, n_channels_bg, n_channels_a); > + adapter->num_in_chan_stats = n_channels_bg + n_channels_a; > adapter->chan_stats = vmalloc(sizeof(*adapter->chan_stats) * > adapter->num_in_chan_stats); > > diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c > index ae9630b49342..9900855746ac 100644 > --- a/drivers/net/wireless/marvell/mwifiex/scan.c > +++ b/drivers/net/wireless/marvell/mwifiex/scan.c > @@ -2492,6 +2492,12 @@ mwifiex_update_chan_statistics(struct mwifiex_private *priv, > sizeof(struct mwifiex_chan_stats); > > for (i = 0 ; i < num_chan; i++) { > + if (adapter->survey_idx >= adapter->num_in_chan_stats) { > + mwifiex_dbg(adapter, WARN, > + "FW reported too many channel results (max %d)\n", > + adapter->num_in_chan_stats); > + return; > + } > chan_stats.chan_num = fw_chan_stats->chan_num; > chan_stats.bandcfg = fw_chan_stats->bandcfg; > chan_stats.flags = fw_chan_stats->flags; > -- > 2.13.2.725.g09c95d1e9-goog > -- Dmitry