'Reasons for WLC_E_DEAUTH_IND / WLAN_REASON_PREV_AUTH_NOT_VALID when roaming'

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List:       hostap
Subject:    Reasons for WLC_E_DEAUTH_IND / WLAN_REASON_PREV_AUTH_NOT_VALID when roaming
From:       Simon Falsig <sfalsig () verity ! ch>
Date:       2020-08-31 15:11:56
Message-ID: GVAP278MB0104FAD8781F4AB03A7126F5BF510 () GVAP278MB0104 ! CHEP278 ! PROD ! OUTLOOK ! COM
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Hi,

I'm trying to debug an issue where Linux-based devices in some, rare cases lose WiFi \
connection after roaming to another access point.

Setup:
 - Stations: Embedded Linux board, running Linux 4.4, wpa_supplicant v2.8, Broadcom \
                WiFi with bcmdhd driver
 - Access Points: Multiple Ubiquity AP-AC-Pro, running, from what I can see, hostapd \
                v2.8 on an Atheros chipset
 - WiFi with WPA2-PSK, 5GHz only, non-DFS channels, coverage of area is not complete

The stations move around within the area, and will thus roam between the access \
points. In some cases, what I see is: 1. The station is connected to access point 1, \
but is moving out of range 2. The station thus attempts to roam to access point 2
3. It connects, but data is no longer coming through
4. After ~4 seconds, I see that the station disconnects due to WLC_E_DEAUTH_IND \
(reason WLAN_REASON_PREV_AUTH_NOT_VALID), received from access point 2 5. The station \
no longer manages to connect to any access point until rebooted (bringing the network \
interface down and back up might also be enough, but am not sure - have not had a \
chance to try this out)

What I'm trying to do now is to replicate this in a controlled environment, but have \
so far been unsuccessful. I'm thus trying to figure out if there are any cases where \
hostapd or wpa_supplicant might cause this to happen?

Until now I've tried:
- Roaming the embedded Linux board between two access points in various \
configurations (channels, TX power, placement of access points, minimum RSSI, de-auth \
                attacks, etc.)
- Looking through the wpa_supplicant / hostapd code, for \
WLAN_REASON_PREV_AUTH_NOT_VALID, but without finding any obvious culprits (admitted, \
with my very limited knowledge of how things work)

I sadly don't have access to the system that exhibited the error in the first place \
any more, and also have a very limited number of logs from failures - I'm limited to \
dmesg logs from the stations, where I'd see things like this: [ 4602.537366] \
CFG80211-ERROR) wl_bss_roaming_done : wl_bss_roaming_done succeeded to \
74:83:c2:b5:7b:90 (ch:48) [ 4602.547672] CFG80211-ERROR) wl_notify_connect_status : \
wl_bss_connect_done succeeded with 74:83:c2:b5:7b:90 [ 4602.597668] CFG80211-ERROR) \
wl_bss_roaming_done : wl_bss_roaming_done succeeded to 74:83:c2:b5:7b:90 (ch:48) [ \
4606.662454] CFG80211-ERROR) wl_is_linkdown : Link down Reason : WLC_E_DEAUTH_IND [ \
4606.669899] CFG80211-ERROR) wl_notify_connect_status : link down if wlan0 may call \
cfg80211_disconnected. event : 6, reason=2 from 74:83:c2:b5:7b:90 [ 4606.685715] \
CFG80211-ERROR) wl_is_linkdown : Link down Reason : WLC_E_DEAUTH [ 4606.703597] \
CFG80211-ERROR) wl_is_linkdown : Link down Reason : WLC_E_DEAUTH [ 4606.711119] \
CFG80211-ERROR) wl_is_linkdown : Link down Reason : WLC_E_DEAUTH [ 4606.720558] \
CFG80211-ERROR) wl_is_linkdown : Link down Reason : WLC_E_DEAUTH [ 4606.727996] \
CFG80211-ERROR) wl_is_linkdown :  [ 4606.728501] cfg80211: World regulatory domain \
updated: [ 4606.728504] cfg80211:  DFS Master region: unset<6>[ 4606.728506] \
cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), \
(dfs_cac_time) [ 4606.728509] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), \
(N/A, 2000 mBm), (N/A) [ 4606.728512] cfg80211:   (2457000 KHz - 2482000 KHz @ 20000 \
KHz, 92000 KHz AUTO), (N/A, 2000 mBm), (N/A) [ 4606.728513] cfg80211:   (2474000 KHz \
- 2494000 KHz @ 20000 KHz), (N/A, 2000 mBm), (N/A) [ 4606.728516] cfg80211:   \
(5170000 KHz - 5250000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (N/A) [ \
4606.728518] cfg80211:   (5250000 KHz - 5330000 KHz @ 80000 KHz, 160000 KHz AUTO), \
(N/A, 2000 mBm), (0 s) [ 4606.728520] cfg80211:   (5490000 KHz - 5730000 KHz @ 160000 \
KHz), (N/A, 2000 mBm), (0 s) [ 4606.728522] cfg80211:   (5735000 KHz - 5835000 KHz @ \
80000 KHz), (N/A, 2000 mBm), (N/A) [ 4606.728524] cfg80211:   (57240000 KHz - \
63720000 KHz @ 2160000 KHz), (N/A, 0 mBm), (N/A) [ 4606.782728] cfg80211: World \
regulatory domain updated: [ 4606.782731] cfg80211:  DFS Master region: unset<6>[ \
4606.782733] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, \
max_eirp), (dfs_cac_time) [ 4606.782739] cfg80211:   (2402000 KHz - 2472000 KHz @ \
40000 KHz), (N/A, 2000 mBm), (N/A) [ 4606.782742] cfg80211:   (2457000 KHz - 2482000 \
KHz @ 20000 KHz, 92000 KHz AUTO), (N/A, 2000 mBm), (N/A) [ 4606.782744] cfg80211:   \
(2474000 KHz - 2494000 KHz @ 20000 KHz), (N/A, 2000 mBm), (N/A) [ 4606.782746] \
cfg80211:   (5170000 KHz - 5250000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 \
mBm), (N/A) [ 4606.782749] cfg80211:   (5250000 KHz - 5330000 KHz @ 80000 KHz, 160000 \
KHz AUTO), (N/A, 2000 mBm), (0 s) [ 4606.782751] cfg80211:   (5490000 KHz - 5730000 \
KHz @ 160000 KHz), (N/A, 2000 mBm), (0 s) [ 4606.782753] cfg80211:   (5735000 KHz - \
5835000 KHz @ 80000 KHz), (N/A, 2000 mBm), (N/A) [ 4606.782755] cfg80211:   (57240000 \
KHz - 63720000 KHz @ 2160000 KHz), (N/A, 0 mBm), (N/A) [ 4606.931747] Link down \
Reason : WLC_E_DEAUTH [ 4606.967191] CFG80211-ERROR) wl_cfg80211_cancel_scan : Scan \
aborted!  [ 4606.973702] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4606.980859] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4606.987956] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4606.995104] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4607.002281] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4607.009374] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4607.016486] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH [ 4607.023627] CFG80211-ERROR) wl_is_linkdown : Link down Reason : \
WLC_E_DEAUTH (...continues...)

I realize that the core issue may very well not have anything to do with hostapd / \
wpa_supplicant, but rather a buggy WiFi driver/firmware somewhere, but any \
input/hints/tips on how to get the issue reproduced would be highly appreciated.

Thanks in advance!
 - Simon

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