netdev - Re: [PATCH] wifi: mac80211: Don't finalize CSA in IBSS mode if state is disconnected

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Date:   Mon, 15 Aug 2022 09:00:13 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Siddh Raman Pant <code@...dh.me>
Cc:     Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        netdev <netdev@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org,
        linux-kernel-mentees 
        <linux-kernel-mentees@...ts.linuxfoundation.org>,
        syzbot+b6c9fe29aefe68e4ad34@...kaller.appspotmail.com
Subject: Re: [PATCH] wifi: mac80211: Don't finalize CSA in IBSS mode if state
 is disconnected

On Sun, Aug 14, 2022 at 08:45:12PM +0530, Siddh Raman Pant via Linux-kernel-mentees wrote:
> When we are not connected to a channel, sending channel "switch"
> announcement doesn't make any sense.
> 
> The BSS list is empty in that case. This causes the for loop in
> cfg80211_get_bss() to be bypassed, so the function returns NULL
> (check line 1424 of net/wireless/scan.c), causing the WARN_ON()
> in ieee80211_ibss_csa_beacon() to get triggered (check line 500
> of net/mac80211/ibss.c), which was consequently reported on the
> syzkaller dashboard.
> 
> Thus, check if we have an existing connection before generating
> the CSA beacon in ieee80211_ibss_finish_csa().
> 
> Fixes: cd7760e62c2a ("mac80211: add support for CSA in IBSS mode")
> Bug report: https://syzkaller.appspot.com/bug?id=05603ef4ae8926761b678d2939a3b2ad28ab9ca6
> Reported-by: syzbot+b6c9fe29aefe68e4ad34@...kaller.appspotmail.com
> Cc: stable@...r.kernel.org
> 
> Signed-off-by: Siddh Raman Pant <code@...dh.me>

Please no blank line before your signed-off-by line or the tools will
not like it.

And did sysbot verify that this change solved the problem?

thanks,

greg k-h