linux-kernel - Re: [PATCH] wifi: mac80211: skip BSS_CHANGED

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Message-ID: <66f082de-8f1e-464d-bedc-41c0a4db1f52@kernel.org>
Date: Sat, 7 Feb 2026 10:41:18 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Dhyan K Prajapati <dhyan19022009@...il.com>,
 Johannes Berg <johannes@...solutions.net>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
 Dhyan K Prajapati <dhyaan19022009@...il.com>
Subject: Re: [PATCH] wifi: mac80211: skip BSS_CHANGED_TXPOWER notification for
 monitor mode

On 07/02/2026 06:00, Dhyan K Prajapati wrote:
> From: Dhyan K Prajapati <dhyaan19022009@...il.com>
> 
> Monitor mode interfaces don't maintain BSS context. The BSS_CHANGED_TXPOWER notification
> indicates transmit power constrains recieved from an associated access point which isn't really
> applicable to monitor mode as it does not associate with any BSS
> 
> after a commit back in july 2025,("wifi: mac80211: fix WARN_ON for monitor mode
> on some devices") monitor interfaces with WANT_MONITOR_VIF began recieving link
> change notifications during ieee_add_virtual_monitor(), when ieee_link_use_channel()
> assigns a channel context it triggers ieee_recalc_power() which sends BSS_CHANGED_TXPOWER
> notifications to driver, driver using legacy bss_info_changed callbeack recieve
> link->conf as the bss_conf parameter for monitor mode that points to vif.bss_conf which is not fully initialised
> in monitor interfaces, so drivers like iwldvm dereference null and crash
> since BSS_CHANGED_TXPOWER notifications are meaningless for monitor mode, we can skip
> the notification entirely,monitor mode transmit power remains configurable via

You keep sending us microslop AI, so I don't think it is worth reviewing it.

> nl80211
> Hardware: Dell Latitude E6430
> Device: Intel Centrino Advanced-N 6205 [Taylor Peak]
> 
> Crash trace:
>   BUG: kernel NULL pointer dereference at 0000000000000000
>   RIP: iwlagn_bss_info_changed+0x19d/0x640 [iwldvm]
>   Call Trace:
>    drv_link_info_changed+0x2b5/0x2c0
>    ieee80211_link_info_change_notify+0x13d/0x160
>    __ieee80211_recalc_txpower+0x44/0xd0
>    ieee80211_recalc_txpower+0x5c/0x60
>    ieee80211_assign_link_chanctx+0x182/0x410
>    ieee80211_link_use_channel+0x413/0x450
>    ieee80211_add_virtual_monitor+0x17c/0x2b0
> 
> Tested-by: Dhyan K Prajapati <dhyan19022009@...il.com>

No, wasn't. AI is not testing.

> Signed-off-by: Dhyan K Prajapati <dhyan19022009@...il.com>
> ---
>  net/mac80211/iface.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)



Best regards,
Krzysztof