linux-kernel - Re: [PATCH] iwlwifi: dvm: fix NULL pointer dereference in rxon

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Message-ID: <540a592bb2604b130e0b21f99e634ac100cee61c.camel@sipsolutions.net>
Date: Wed, 04 Feb 2026 14:07:13 +0100
From: Johannes Berg <johannes@...solutions.net>
To: dhyaan19022009-hue <dhyan19022009@...il.com>
Cc: kvalo@...nel.org, linux-wireless@...r.kernel.org, 
	linux-kernel@...r.kernel.org, dhyaan19022009-hue <dhyaan19022009@...il.com>
Subject: Re: [PATCH] iwlwifi: dvm: fix NULL pointer dereference in rxon

On Wed, 2026-02-04 at 18:23 +0530, dhyaan19022009-hue wrote:
> When bringing up the wireless interface via virtual monitor mode,
> iwlagn_bss_info_changed() can be called with a vif that has no
> associated rxon context. This occurs during the
> ieee80211_add_virtual_monitor() -> ieee80211_do_open() sequence.
> 
> The function iwl_rxon_ctx_from_vif() returns NULL for virtual monitor
> interfaces, causing a NULL pointer dereference when the code attempts
> to access ctx fields at offset +0x10.
> 
> Crash signature:
>   BUG: kernel NULL pointer dereference, address: 0000000000000000
>   RIP: 0010:iwlagn_bss_info_changed+0x19d/0x640 [iwldvm]
>   Call Trace:
>    drv_link_info_changed+0x2b5/0x2c0 [mac80211]
>    ieee80211_link_info_change_notify+0x13d/0x160 [mac80211]
>    ieee80211_recalc_txpower+0x5c/0x60 [mac80211]
>    ieee80211_assign_link_chanctx+0x182/0x410 [mac80211]
>    ieee80211_add_virtual_monitor+0x17c/0x2b0 [mac80211]
>    ieee80211_do_open+0x6d8/0x740 [mac80211]
> 
> Add an early NULL check for ctx before accessing its members.
> 
> Hardware: Dell Latitude E6430
> WiFi: Intel Centrino Advanced-N 6205 [8086:0085]
> Kernel: 6.18.7-061807-generic
> 
> Reported-by: Johannes Berg <johannes@...solutions.net>

Yeah, no. Please find someone who's willing to teach you first.

johannes