wifi: mac80211: don't seed an S1G sta's last_rate

When initialising the rate control system, ieee80211_s1g_sta_rate_init()
is called for S1G stations during association where it initialises a
last rate of type STA_STATS_RATE_TYPE_S1G but does not initialise
nss, mcs bw etc. Since the last_rate no longer has a value equivalent
to STA_STATS_RATE_INVALID, the invalid rate will be decoded and
the NL80211_STA_INFO_RX_BITRATE flag will be set.

As a result, there is a period during association before the first
data frame is rx'ed where the seeded value is overwritten by
ieee80211_rx_h_sta_process() while this invalid last_rate lives. If
the sta is desroyed during this process, nl80211_put_sta_rate() will
call into cfg80211_calculate_bitrate() and attempt to calculate
the bitrate using the invalid last_rate leading to a WARN:

4,336,675067400,-;------------[ cut here ]------------
4,337,675067524,-;WARNING: net/wireless/util.c:1960 at cfg80211_calculate_bitrate+0x4d8/0x8b0 [cfg80211], CPU#3: kworker/u16:3/874
4,338,675068176,-;invalid rate bw=0, mcs=0, nss=0
[snip loaded modules]
4,341,675068954,-;Hardware name: BCM2711
4,342,675068961,-;Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]
4,343,675069386,-;Call trace:
4,344,675069392,-; unwind_backtrace from show_stack+0x10/0x14
4,345,675069440,-; show_stack from dump_stack_lvl+0xa8/0xb8
4,346,675069475,-; dump_stack_lvl from __warn+0x90/0x224
4,347,675069517,-; __warn from warn_slowpath_fmt+0x130/0x1a8
4,348,675069559,-; warn_slowpath_fmt from cfg80211_calculate_bitrate+0x4d8/0x8b0 [cfg80211]
4,349,675070005,-; cfg80211_calculate_bitrate [cfg80211] from nl80211_put_sta_rate+0x48/0x590 [cfg80211]
4,350,675070819,-; nl80211_put_sta_rate [cfg80211] from nl80211_put_sta_info_common+0x4f4/0xd50 [cfg80211]
4,351,675071616,-; nl80211_put_sta_info_common [cfg80211] from nl80211_send_station.constprop.0+0x114/0x424 [cfg80211]
4,352,675072427,-; nl80211_send_station.constprop.0 [cfg80211] from cfg80211_del_sta_sinfo+0xc4/0x368 [cfg80211]
4,353,675073222,-; cfg80211_del_sta_sinfo [cfg80211] from __sta_info_destroy_part2+0x108/0x2c0 [mac80211]
4,354,675074178,-; __sta_info_destroy_part2 [mac80211] from sta_info_destroy_addr+0x4c/0x88 [mac80211]
4,355,675075243,-; sta_info_destroy_addr [mac80211] from ieee80211_destroy_assoc_data+0x194/0x2d8 [mac80211]
4,356,675075920,-; ieee80211_destroy_assoc_data [mac80211] from ieee80211_rx_mgmt_assoc_resp+0x220/0x1d4c [mac80211]
4,357,675076558,-; ieee80211_rx_mgmt_assoc_resp [mac80211] from ieee80211_iface_work+0x1c0/0x5d0 [mac80211]
4,358,675077187,-; ieee80211_iface_work [mac80211] from cfg80211_wiphy_work+0x110/0x368 [cfg80211]
4,359,675077763,-; cfg80211_wiphy_work [cfg80211] from process_one_work+0x260/0x868
4,360,675078022,-; process_one_work from worker_thread+0x1bc/0x3ec
4,361,675078042,-; worker_thread from kthread+0x120/0x154
4,362,675078060,-; kthread from ret_from_fork+0x14/0x20
4,363,675078074,-;Exception stack(0xf0ac1fb0 to 0xf0ac1ff8)
4,364,675078081,-;1fa0:                                     00000000 00000000 00000000 00000000
4,365,675078088,-;1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
4,366,675078093,-;1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
4,367,675080226,-;irq event stamp: 15780967
4,368,675080287,-;hardirqs last  enabled at (15780975): [<c050c154>] __up_console_sem+0x50/0x60
4,369,675080395,-;hardirqs last disabled at (15780982): [<c050c140>] __up_console_sem+0x3c/0x60
4,370,675080497,-;softirqs last  enabled at (15780966): [<c0476f14>] handle_softirqs+0x398/0x650
4,371,675080608,-;softirqs last disabled at (15780939): [<c0477388>] __irq_exit_rcu+0x150/0x1f0
4,372,675080715,-;---[ end trace 0000000000000000 ]---

To fix, we can simply not seed this psuedo rate. It was originally
implemented to avoid errornous paths that S1G shouldn't take, but those
have since been fixed / cleaned up. While we are here, we also don't
need to initialise the tx side's last rate with
IEEE80211_TX_RC_S1G_MCS (which is equivalent to
IEEE80211_TX_RC_VHT_MCS). The entire tx reporting side does not
support S1G widths and is assumed to be handled by the driver so
we can just remove the entire function.

Fixes: 12bf8fad4ca3 ("mac80211: initialize last_rate for S1G STAs")
Signed-off-by: Lachlan Hodges <lachlan.hodges@morsemicro.com>
Link: https://patch.msgid.link/20260827054456.254573-1-lachlan.hodges@morsemicro.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

0 files changed, 0 insertions, 0 deletions