wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon

mirror of https://github.com/outbackdingo/mt76.git synced 2026-10-24 13:26:48 +00:00

This patch is based on a BUG as reported by Bongani Hlope at
https://lore.kernel.org/all/[email protected]/

When a channel-switch announcement (CSA) beacon is received,
cfg80211 queues a wiphy work item that eventually calls
mt7921_channel_switch_rx_beacon(). If the station disconnects
(or the channel context is otherwise torn down) between the
time the work is queued and the time it runs, the driver's
dev->new_ctx pointer can already have been cleared to NULL.
mt7921_channel_switch_rx_beacon() then dereferences new_ctx
unconditionally, triggering a NULL pointer dereference at
address 0x0:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  RIP: 0010:mt7921_channel_switch_rx_beacon+0x1f/0x100 [mt7921_common]

The same missing guard exists in mt7925_channel_switch_rx_beacon(),
which shares the same code pattern introduced by the same commit.

Add an early-return NULL check for dev->new_ctx in both
mt7921_channel_switch_rx_beacon() and
mt7925_channel_switch_rx_beacon(). When new_ctx is NULL there is
no pending channel switch to process, so returning immediately is
the correct and safe action.

Fixes: 8aa2f59260eb ("wifi: mt76: mt7921: introduce CSA support")
Reported-by: Bongani Hlope <[email protected]>
Oops-Analysis: http://oops.fenrus.org/reports/lkml/[email protected]/report.html
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Arjan van de Ven <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Felix Fietkau <[email protected]>
Cc: Lorenzo Bianconi <[email protected]>
Cc: Ryder Lee <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>

This commit is contained in:

Arjan van de Ven

2026-05-12 13:08:20 +00:00

committed by

Felix Fietkau

parent d463ed9490

commit dd1459c0c7

2 changed files with 6 additions and 0 deletions

									
										mt7921/main.c
									
		+3
		
												View File
												
				@@ -1511,6 +1511,9 @@ static void mt7921_channel_switch_rx_beacon(struct ieee80211_hw *hw,

					struct mt792x_vif *mvif = (struct mt792x_vif *)vif->drv_priv;

					u16 beacon_interval = vif->bss_conf.beacon_int;

					if (!dev->new_ctx)

						return;

					if (cfg80211_chandef_identical(&chsw->chandef,

								       &dev->new_ctx->def) &&

								       chsw->count) {