Re: kern/144987: [wpi] [panic] injecting packets with wlaninject using Intel 3945ABG wireless card gives kernel panic

The following reply was made to PR kern/144987; it has been noted by GNATS.

From: Bernhard Schmidt <bschmidt@xxxxxxxxxxx>
To: bug-followup@xxxxxxxxxxx,
gabrielquadros@xxxxxxxxxxx
Cc: Julian Elischer <julian@xxxxxxxxxxx>
Subject: Re: kern/144987: [wpi] [panic] injecting packets with wlaninject using Intel 3945ABG wireless card gives kernel panic
Date: Wed, 22 Dec 2010 09:58:34 +0100

On Monday 20 December 2010 15:10:02 Bernhard Schmidt wrote:
Hi,

The issue here is that you've tried to use wlaninject with a VAP in sta
mode. As soon as wlaninject tries to set up the interface, net80211 will
start to do a scan which means constant channel switches until it finds
something to associate. wlaninject itself is not aware of that and happily
injects frames no matter what the current channel state is, as the above
trace shows, you hit a point where no channel is set between 2 scan
interations.

wlaninject is supposed to be used with VAPs in ahdemo mode and wpi(4) does
not support that mode. Therefore I tend to close this PR.

Looking closer I might have been a bit wrong. There are several issue here..
One being that ni_chan is used in the TX path which should and can actually be
replaced by ic_curchan. This will fix the panic reported above, though, this
does no longer obscure other issues. For examples, we are allowed to pass in
frames of arbitrary length, extremely short frames will be discarded early due
to an overflow checking the length (the message to long error). But, if the
length is just long enough to reach the driver it might still be shorter then
the header for a 802.11 frame. This will result in another panic() in
m_copydata() as we try to copy over the header to firmware..

I'll try to find a useful solution for that.

--
Bernhard
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