Return-path: Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:48614 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751563AbdF3SNY (ORCPT ); Fri, 30 Jun 2017 14:13:24 -0400 From: Ganapathi Bhat To: Brian Norris CC: Nishant Sarmukadam , Kalle Valo , "linux-kernel@vger.kernel.org" , Amitkumar Karwar , "linux-wireless@vger.kernel.org" , "stable@vger.kernel.org" , Avinash Patil , Xinming Hu , Dmitry Torokhov Subject: RE: [EXT] Re: [PATCH] mwifiex: correct channel stat buffer overflows Date: Fri, 30 Jun 2017 18:13:19 +0000 Message-ID: (sfid-20170630_201353_338084_251515BA) References: <20170630012354.98931-1-briannorris@chromium.org> <20170630180439.GA40906@dtor-ws> In-Reply-To: <20170630180439.GA40906@dtor-ws> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi Brian, > ---------------------------------------------------------------------- > 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 > Changes look good. Reviewed-by: Ganapathi Bhat > > > > 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 Regards, Ganapathi