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Ticket #250 (assigned defect)

Opened 16 years ago

Last modified 14 years ago

madwifi-ng crashes when switching xr on while in STA mode

Reported by: svens Assigned to: mrenzmann (accepted)
Priority: major Milestone: version 1.0.0 - first stable release
Component: madwifi: driver Version: trunk
Keywords: xr Cc:
Patch is attached: 0 Pending:


Switching on XR with iwpriv wlan0 xr 1 in STA mode leads reproducable to the attached kernel oops. Thats because ic->ic_vap_create in ieee80211_setupxr() returns NULL, which is dereferenced later on.


madwifi-xr-oops (3.4 kB) - added by svens on 12/21/05 21:25:46.
oops output
madwifi-xr-segfault (2.0 kB) - added by on 03/15/06 12:19:23.

Change History

12/21/05 21:25:46 changed by svens

  • attachment madwifi-xr-oops added.

oops output

12/27/05 16:18:25 changed by mrenzmann

Do you think you can provide a patch for this issue?

01/04/06 01:12:32 changed by svens

Don't think so, since i don't have any specification how xr is working...

01/27/06 11:54:59 changed by mrenzmann

As mentioned here:

ic->ic_vap_create returned NULL because

	 if ((sc->sc_nvaps != 0) && (ic->ic_opmode == IEEE80211_M_STA))
			return NULL;

in ath_vap_create function.

Which makes me wonder...

  • ... I am right with interpreting that code such that it isn't allowed to enable XR on a STA VAP
  • ... why that is the case

01/27/06 12:01:20 changed by mrenzmann

Forgot to mention: question forwarded to Atheros today.

01/30/06 07:02:24 changed by mrenzmann

  • status changed from new to assigned.
  • owner set to mrenzmann.

Answer from Atheros: XR is implemented for STA mode only so far. There has been no need for XR in master mode yet, so this is simply missing. I've now asked Atheros if it would be possible to hand us the necessary information to implement XR for other modes than STA as well.


  • it is valid for ieee80211_setupxr() to return NULL, so this should be expected and properly handled; will take care to provide a patch for this
  • this fact needs to be documented, in the wiki as well as in the users-guide; any volunteers?

01/31/06 08:00:15 changed by svens

read above "Answer from Atheros: XR is implemented for AP mode only so far." So we should add a sanity check and leave the rest of the code as it is until we get some code that implements this functionality for STA mode.

03/15/06 12:18:23 changed by

  • patch_attached changed.

I also get a segfault with 1474 when running master mode.

03/15/06 12:19:23 changed by

  • attachment madwifi-xr-segfault added.

06/13/06 01:22:59 changed by

I am using madwifi-ng 0.1531.20060427 and have the same problem. when i Try to swith the extended range feature on with iwpriv ath0 xr 1

i get this: Unable to handle kernel NULL pointer dereference at virtual address 000002fa Jun 13 01:10:11 [kernel] printing eip: Jun 13 01:10:11 [kernel] f0963bcb Jun 13 01:10:11 [kernel] *pde = 00000000 Jun 13 01:10:11 [kernel] Modules linked in: wlan_scan_sta ath_pci ath_rate_sample wlan ath_hal Jun 13 01:10:11 [kernel] EIP: 0060:[<f0963bcb>] Tainted: P VLI Jun 13 01:10:11 [kernel] EFLAGS: 00010292 (2.6.16-suspend2-r4 #1)

Few minutes later my keyboard stops working, mouse is still ok, i have to reboot to be able to type again. I'm using that minipci card:

Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC (rev 01)

Any solution?

(follow-up: ↓ 10 ) 07/26/06 12:22:12 changed by awalton

After using the 1.9.1 code I assume you have circumvented the problem by making it impossible to set XR when configured in STA mode. I just wonder what is the point of XR capability in AP mode only? From what I undetstand XR increases the RX sensitivity to -105dBm. Surely this is only usable if both AP and STA have increased sensitivity, otherwise you will have communication possible in only one direction?

(in reply to: ↑ 9 ) 06/19/07 01:00:22 changed by

Replying to awalton: I agree with AWALTON.