When userspace creates a new hwsim radio with both
HWSIM_ATTR_MULTI_RADIO and HWSIM_ATTR_SUPPORT_NAN_DEVICE,
hwsim_new_radio_nl() sets BIT(NL80211_IFTYPE_NAN_DATA) in
wiphy->interface_modes while configuring the wiphy with
n_radio > 1. This violates the invariant checked in
wiphy_register():

    (interface_modes & BIT(NL80211_IFTYPE_NAN_DATA)) &&
    (!nan_capa.phy.ht.ht_supported || n_radio > 1)

triggering a WARN reachable from userspace via genetlink.
With panic_on_warn this becomes a denial of service.

Refuse the combination at parse time with -EINVAL and an
extack message, matching the cfg80211 constraint that NAN
is not supported on multi-radio wiphys.

Reported-by: syzbot+2002864e6c6895cb0ac3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2002864e6c6895cb0ac3
Fixes: 2c7c70ee7cee ("wifi: mac80211_hwsim: enable NAN_DATA interface simulation support")
Tested-by: syzbot+2002864e6c6895cb0ac3@syzkaller.appspotmail.com
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
 drivers/net/wireless/virtual/mac80211_hwsim_main.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/virtual/mac80211_hwsim_main.c b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
index dc9775cd9f54..a625a9e3caa7 100644
--- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
@@ -6766,9 +6766,15 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
 		param.p2p_device = true;
 	}
 
-	if (param.nan_device)
+	if (param.nan_device) {
+		if (param.multi_radio) {
+			NL_SET_ERR_MSG(info->extack,
+				       "NAN is not supported on multi-radio wiphys");
+			return -EINVAL;
+		}
 		param.iftypes |= BIT(NL80211_IFTYPE_NAN) |
 				 BIT(NL80211_IFTYPE_NAN_DATA);
+	}
 
 	if (info->attrs[HWSIM_ATTR_CIPHER_SUPPORT]) {
 		u32 len = nla_len(info->attrs[HWSIM_ATTR_CIPHER_SUPPORT]);
-- 
2.43.0