wifi: ath11k: fix NULL pointer dereference in ath11k_mac_get_eirp_power()

Commit 39dc8b8 ("wifi: mac80211: pass parsed TPE data to drivers") breaks
ath11k, leading to kernel crash:

BUG: kernel NULL pointer dereference, address: 0000000000000018
RIP: 0010:ath11k_mac_get_eirp_power.isra.0+0x5b/0x80 [ath11k]
Call Trace:
 <TASK>
 ath11k_mac_fill_reg_tpc_info+0x3d6/0x800 [ath11k]
 ath11k_mac_vdev_start_restart+0x412/0x4d0 [ath11k]
 ath11k_mac_op_sta_state+0x7bc/0xbb0 [ath11k]
 drv_sta_state+0xf1/0x5f0 [mac80211]
 sta_info_insert_rcu+0x28d/0x530 [mac80211]
 sta_info_insert+0xf/0x20 [mac80211]
 ieee80211_prep_connection+0x3b4/0x4c0 [mac80211]
 ieee80211_mgd_auth+0x363/0x600 [mac80211]

The issue scenario is, AP advertises power spectral density (PSD) values in its
transmit power envelope (TPE) IE and supports 160 MHz bandwidth in 6 GHz. When
connecting to this AP, in ath11k_mac_parse_tx_pwr_env(), the local variable
psd is true and then reg_tpc_info.num_pwr_levels is set to 8 due to 160 MHz
bandwidth. Note here ath11k fails to set reg_tpc_info.is_psd_power as TRUE due
to above commit. Then in ath11k_mac_fill_reg_tpc_info(), for each of the 8
power levels, for a PSD channel, ath11k_mac_get_psd_channel() is expected to
be called to get required information. However due to invalid
reg_tpc_info.is_psd_power, it is ath11k_mac_get_eirp_power() that gets called
and passed with pwr_lvl_idx as one of the arguments. Note this function
implicitly requires pwr_lvl_idx to be no more than 3. So when pwr_lvl_idx is
larger than that ath11k_mac_get_seg_freq() returns invalid center frequency,
with which as the input ieee80211_get_channel() returns NULL, then kernel
crashes due to NULL pointer dereference.

Fix it by setting reg_tpc_info.is_psd_power properly.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30

Fixes: 39dc8b8 ("wifi: mac80211: pass parsed TPE data to drivers")
Reported-by: Mikko Tiihonen <[email protected]>
Tested-by: Mikko Tiihonen <[email protected]>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219131
Signed-off-by: Baochen Qiang <[email protected]>
Acked-by: Jeff Johnson <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: Baochen Qiang

drivers/net/wireless/ath/ath11k/mac.c

@@ -7900,6 +7900,7 @@ static void ath11k_mac_parse_tx_pwr_env(struct ath11k *ar,
 	}
 
 	if (psd) {
+		arvif->reg_tpc_info.is_psd_power = true;
 		arvif->reg_tpc_info.num_pwr_levels = psd->count;
 
 		for (i = 0; i < arvif->reg_tpc_info.num_pwr_levels; i++) {