[PATCH 3.16 206/254] mac80211_hwsim: validate number of different channels

[Ben Hutchings]

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@xxxxxxxxx>

commit 51a1aaa631c90223888d8beac4d649dc11d2ca55 upstream.

When creating a new radio on the fly, hwsim allows this
to be done with an arbitrary number of channels, but
cfg80211 only supports a limited number of simultaneous
channels, leading to a warning.

Fix this by validating the number - this requires moving
the define for the maximum out to a visible header file.

Reported-by: syzbot+8dd9051ff19940290931@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: b59ec8dd4394 ("mac80211_hwsim: fix number of channels in interface combinations")
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
[bwh: Backported to 3.16:
 - Test chans intead of param.channels
 - GENL_SET_ERR_MSG() is not available
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -2439,6 +2439,9 @@ static int hwsim_create_radio_nl(struct
 	if (info->attrs[HWSIM_ATTR_CHANNELS])
 		chans = nla_get_u32(info->attrs[HWSIM_ATTR_CHANNELS]);
 
+	if (chans > CFG80211_MAX_NUM_DIFFERENT_CHANNELS)
+		return -EINVAL;
+
 	if (info->attrs[HWSIM_ATTR_USE_CHANCTX])
 		use_chanctx = true;
 	else
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -716,6 +716,8 @@ struct cfg80211_csa_settings {
 	u8 count;
 };
 
+#define CFG80211_MAX_NUM_DIFFERENT_CHANNELS 10
+
 /**
  * enum station_parameters_apply_mask - station parameter values to apply
  * @STATION_PARAM_APPLY_UAPSD: apply new uAPSD parameters (uapsd_queues, max_sp)
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -456,8 +456,6 @@ void cfg80211_leave(struct cfg80211_regi
 void cfg80211_stop_p2p_device(struct cfg80211_registered_device *rdev,
 			      struct wireless_dev *wdev);
 
-#define CFG80211_MAX_NUM_DIFFERENT_CHANNELS 10
-
 #ifdef CONFIG_CFG80211_DEVELOPER_WARNINGS
 #define CFG80211_DEV_WARN_ON(cond)	WARN_ON(cond)
 #else