[PATCH] wifi: mt76: mt7925: fix crash in reset link replay

[PATCH] wifi: mt76: mt7925: fix crash in reset link replay

[Sean Wang]

From: Sean Wang <sean.wang@mediatek.com>

During reset recovery, mt7925_vif_connect_iter() replays firmware state
for links tracked in mvif->valid_links. After MLO link changes or MCU
timeout recovery, the driver bitmap can temporarily contain a link whose
mac80211 bss_conf has already gone away.

This can pass a NULL bss_conf to mt76_connac_mcu_uni_add_dev(), matching
the crash where x1, the second argument, is NULL:

pc : mt76_connac_mcu_uni_add_dev+0x8c/0x1f8 [mt76_connac_lib]
lr : mt7925_vif_connect_iter+0x9c/0x168 [mt7925_common]
x2 : ffffff80a77f6018 x1 : 0000000000000000 x0 : ffffff8099402080
Call trace:
mt76_connac_mcu_uni_add_dev+0x8c/0x1f8 [mt76_connac_lib]
mt7925_vif_connect_iter+0x9c/0x168 [mt7925_common]
mt7925_mac_reset_work+0x264/0x2f8 [mt7925_common]

Skip missing bss_conf entries before replaying the link. Non-MLO AP/STA
reset replay is unchanged because the helper still returns &vif->bss_conf
for the legacy link.

Fixes: 14061994184d ("wifi: mt76: mt7925: add link handling in mt7925_vif_connect_iter")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7925/mac.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
index d7e4ebe92342..cee4e4b8ff41 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
@@ -1284,6 +1284,9 @@ mt7925_vif_connect_iter(void *priv, u8 *mac,
 
 	for_each_set_bit(i, &valid, IEEE80211_MLD_MAX_NUM_LINKS) {
 		bss_conf = mt792x_vif_to_bss_conf(vif, i);
+		if (!bss_conf)
+			continue;
+
 		mconf = mt792x_vif_to_link(mvif, i);
 
 		mt76_connac_mcu_uni_add_dev(&dev->mphy, bss_conf, &mconf->mt76,
-- 
2.43.0