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 <dev> 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: <stable@xxxxxxxxxxxxxxx>
> Cc: Avinash Patil <patila@xxxxxxxxxxx>
> Cc: Xinming Hu <huxm@xxxxxxxxxxx>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> ---
> 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 <dmitry.torokhov@xxxxxxxxx>
>
> 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
