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Thu, 29 Jan 2026 00:18:48 -0800 (PST) Sender: Zac Bowling From: Zac To: nbd@nbd.name Cc: deren.wu@mediatek.com, kvalo@kernel.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-wireless@vger.kernel.org, linux@frame.work, lorenzo@kernel.org, ryder.lee@mediatek.com, sean.wang@kernel.org, sean.wang@mediatek.com, zac@zacbowling.com, zbowling@gmail.com Subject: [PATCH v7 2/6] wifi: mt76: mt7925: add NULL pointer protection for MLO state transitions Date: Thu, 29 Jan 2026 00:18:35 -0800 Message-ID: <20260129081839.179709-3-zac@zacbowling.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260129081839.179709-1-zac@zacbowling.com> References: <20260129081839.179709-1-zac@zacbowling.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add NULL pointer checks for functions that return pointers to link-related structures throughout the mt7925 driver. During MLO state transitions, these functions can return NULL when link configuration is not synchronized. Functions protected: - mt792x_vif_to_bss_conf(): Returns link BSS configuration - mt792x_vif_to_link(): Returns driver link state - mt792x_sta_to_link(): Returns station link state Key changes: 1. mt7925_set_link_key(): - Check link_conf, mconf, mlink before use - During MLO roaming, allow key removal to succeed if link is already go= ne 2. mt7925_mac_link_sta_add(): - Check mlink and mconf before WCID allocation - Check link_conf before BSS info update - Add proper WCID cleanup on error paths (err_wcid label) - Check MCU return values and propagate errors 3. mt7925_mac_link_sta_assoc(): - Check mlink before use - Check link_conf and mconf before BSS info update 4. mt7925_mac_link_sta_remove(): - Check mlink before use - Check link_conf and mconf before cleanup operations Prevents crashes during: - BSSID roaming transitions - MLO setup and teardown - Hardware reset operations Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt= 7925 device") Signed-off-by: Zac Bowling --- .../net/wireless/mediatek/mt76/mt7925/main.c | 66 ++++++++++++++----- 1 file changed, 51 insertions(+), 15 deletions(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/main.c b/drivers/net= /wireless/mediatek/mt76/mt7925/main.c index fad3b1505f67..88ee90709b75 100644 --- a/drivers/net/wireless/mediatek/mt76/mt7925/main.c +++ b/drivers/net/wireless/mediatek/mt76/mt7925/main.c @@ -612,6 +612,17 @@ static int mt7925_set_link_key(struct ieee80211_hw *hw= , enum set_key_cmd cmd, link_sta =3D sta ? mt792x_sta_to_link_sta(vif, sta, link_id) : NULL; mconf =3D mt792x_vif_to_link(mvif, link_id); mlink =3D mt792x_sta_to_link(msta, link_id); + + if (!link_conf || !mconf || !mlink) { + /* During MLO roaming, link state may be torn down before + * mac80211 requests key removal. If removing a key and + * the link is already gone, consider it successfully removed. + */ + if (cmd !=3D SET_KEY) + return 0; + return -EINVAL; + } + wcid =3D &mlink->wcid; wcid_keyidx =3D &wcid->hw_key_idx; =20 @@ -864,12 +875,17 @@ static int mt7925_mac_link_sta_add(struct mt76_dev *m= dev, =20 msta =3D (struct mt792x_sta *)link_sta->sta->drv_priv; mlink =3D mt792x_sta_to_link(msta, link_id); + if (!mlink) + return -EINVAL; + + mconf =3D mt792x_vif_to_link(mvif, link_id); + if (!mconf) + return -EINVAL; =20 idx =3D mt76_wcid_alloc(dev->mt76.wcid_mask, MT792x_WTBL_STA - 1); if (idx < 0) return -ENOSPC; =20 - mconf =3D mt792x_vif_to_link(mvif, link_id); mt76_wcid_init(&mlink->wcid, 0); mlink->wcid.sta =3D 1; mlink->wcid.idx =3D idx; @@ -888,21 +904,28 @@ static int mt7925_mac_link_sta_add(struct mt76_dev *m= dev, =20 ret =3D mt76_connac_pm_wake(&dev->mphy, &dev->pm); if (ret) - return ret; + goto err_wcid; =20 mt7925_mac_wtbl_update(dev, idx, MT_WTBL_UPDATE_ADM_COUNT_CLEAR); =20 link_conf =3D mt792x_vif_to_bss_conf(vif, link_id); + if (!link_conf) { + ret =3D -EINVAL; + goto err_wcid; + } =20 /* should update bss info before STA add */ if (vif->type =3D=3D NL80211_IFTYPE_STATION && !link_sta->sta->tdls) { if (ieee80211_vif_is_mld(vif)) - mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, - link_conf, link_sta, link_sta !=3D mlink->pri_link); + ret =3D mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, + link_conf, link_sta, + link_sta !=3D mlink->pri_link); else - mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, - link_conf, link_sta, false); + ret =3D mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, + link_conf, link_sta, false); + if (ret) + goto err_wcid; } =20 if (ieee80211_vif_is_mld(vif) && @@ -910,28 +933,34 @@ static int mt7925_mac_link_sta_add(struct mt76_dev *m= dev, ret =3D mt7925_mcu_sta_update(dev, link_sta, vif, true, MT76_STA_INFO_STATE_NONE); if (ret) - return ret; + goto err_wcid; } else if (ieee80211_vif_is_mld(vif) && link_sta !=3D mlink->pri_link) { ret =3D mt7925_mcu_sta_update(dev, mlink->pri_link, vif, true, MT76_STA_INFO_STATE_ASSOC); if (ret) - return ret; + goto err_wcid; =20 ret =3D mt7925_mcu_sta_update(dev, link_sta, vif, true, MT76_STA_INFO_STATE_ASSOC); if (ret) - return ret; + goto err_wcid; } else { ret =3D mt7925_mcu_sta_update(dev, link_sta, vif, true, MT76_STA_INFO_STATE_NONE); if (ret) - return ret; + goto err_wcid; } =20 mt76_connac_power_save_sched(&dev->mphy, &dev->pm); =20 return 0; + +err_wcid: + rcu_assign_pointer(dev->mt76.wcid[idx], NULL); + mt76_wcid_mask_clear(dev->mt76.wcid_mask, idx); + mt76_connac_power_save_sched(&dev->mphy, &dev->pm); + return ret; } =20 static int @@ -1039,6 +1068,8 @@ static void mt7925_mac_link_sta_assoc(struct mt76_dev= *mdev, =20 msta =3D (struct mt792x_sta *)link_sta->sta->drv_priv; mlink =3D mt792x_sta_to_link(msta, link_sta->link_id); + if (!mlink) + return; =20 mt792x_mutex_acquire(dev); =20 @@ -1048,12 +1079,13 @@ static void mt7925_mac_link_sta_assoc(struct mt76_d= ev *mdev, link_conf =3D mt792x_vif_to_bss_conf(vif, vif->bss_conf.link_id); } =20 - if (vif->type =3D=3D NL80211_IFTYPE_STATION && !link_sta->sta->tdls) { + if (link_conf && vif->type =3D=3D NL80211_IFTYPE_STATION && !link_sta->st= a->tdls) { struct mt792x_bss_conf *mconf; =20 mconf =3D mt792x_link_conf_to_mconf(link_conf); - mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, - link_conf, link_sta, true); + if (mconf) + mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, + link_conf, link_sta, true); } =20 ewma_avg_signal_init(&mlink->avg_ack_signal); @@ -1100,6 +1132,8 @@ static void mt7925_mac_link_sta_remove(struct mt76_de= v *mdev, =20 msta =3D (struct mt792x_sta *)link_sta->sta->drv_priv; mlink =3D mt792x_sta_to_link(msta, link_id); + if (!mlink) + return; =20 mt7925_roc_abort_sync(dev); =20 @@ -1113,10 +1147,12 @@ static void mt7925_mac_link_sta_remove(struct mt76_= dev *mdev, =20 link_conf =3D mt792x_vif_to_bss_conf(vif, link_id); =20 - if (vif->type =3D=3D NL80211_IFTYPE_STATION && !link_sta->sta->tdls) { + if (link_conf && vif->type =3D=3D NL80211_IFTYPE_STATION && !link_sta->st= a->tdls) { struct mt792x_bss_conf *mconf; =20 mconf =3D mt792x_link_conf_to_mconf(link_conf); + if (!mconf) + goto out; =20 if (ieee80211_vif_is_mld(vif)) mt792x_mac_link_bss_remove(dev, mconf, mlink); @@ -1124,7 +1160,7 @@ static void mt7925_mac_link_sta_remove(struct mt76_de= v *mdev, mt7925_mcu_add_bss_info(&dev->phy, mconf->mt76.ctx, link_conf, link_sta, false); } - +out: spin_lock_bh(&mdev->sta_poll_lock); if (!list_empty(&mlink->wcid.poll_list)) list_del_init(&mlink->wcid.poll_list); --=20 2.52.0