mt76: fix use-after-free by removing a non-RCU wcid pointer

nbd168 · nbd168 · commit 51fb1278aa57 · 2022-05-13T09:39:34.000+02:00
Fixes an issue caught by KASAN about use-after-free in mt76_txq_schedule by protecting mtxq->wcid with rcu_lock between mt76_txq_schedule and sta_info_[alloc, free]. [18853.876689] ================================================================== [18853.876751] BUG: KASAN: use-after-free in mt76_txq_schedule+0x204/0xaf8 [mt76] [18853.876773] Read of size 8 at addr ffffffaf989a2138 by task mt76-tx phy0/883 [18853.876786] [18853.876810] CPU: 5 PID: 883 Comm: mt76-tx phy0 Not tainted 5.10.100-fix-510-56778d365941-kasan #5 0b01fbbcf41a530f52043508fec2e31a4215 [18853.876840] Call trace: [18853.876861] dump_backtrace+0x0/0x3ec [18853.876878] show_stack+0x20/0x2c [18853.876899] dump_stack+0x11c/0x1ac [18853.876918] print_address_description+0x74/0x514 [18853.876934] kasan_report+0x134/0x174 [18853.876948] __asan_report_load8_noabort+0x44/0x50 [18853.876976] mt76_txq_schedule+0x204/0xaf8 [mt76 074e03e4640e97fe7405ee1fab547b81c4fa45d2] [18853.877002] mt76_txq_schedule_all+0x2c/0x48 [mt76 074e03e4640e97fe7405ee1fab547b81c4fa45d2] [18853.877030] mt7921_tx_worker+0xa0/0x1cc [mt7921_common f0875ebac9d7b4754e1010549e7db50fbd90a047] [18853.877054] __mt76_worker_fn+0x190/0x22c [mt76 074e03e4640e97fe7405ee1fab547b81c4fa45d2] [18853.877071] kthread+0x2f8/0x3b8 [18853.877087] ret_from_fork+0x10/0x30 [18853.877098] [18853.877112] Allocated by task 941: [18853.877131] kasan_save_stack+0x38/0x68 [18853.877147] __kasan_kmalloc+0xd4/0xfc [18853.877163] kasan_kmalloc+0x10/0x1c [18853.877177] __kmalloc+0x264/0x3c4 [18853.877294] sta_info_alloc+0x460/0xf88 [mac80211] [18853.877410] ieee80211_prep_connection+0x204/0x1ee0 [mac80211] [18853.877523] ieee80211_mgd_auth+0x6c4/0xa4c [mac80211] [18853.877635] ieee80211_auth+0x20/0x2c [mac80211] [18853.877733] rdev_auth+0x7c/0x438 [cfg80211] [18853.877826] cfg80211_mlme_auth+0x26c/0x390 [cfg80211] [18853.877919] nl80211_authenticate+0x6d4/0x904 [cfg80211] [18853.877938] genl_rcv_msg+0x748/0x93c [18853.877954] netlink_rcv_skb+0x160/0x2a8 [18853.877969] genl_rcv+0x3c/0x54 [18853.877985] netlink_unicast_kernel+0x104/0x1ec [18853.877999] netlink_unicast+0x178/0x268 [18853.878015] netlink_sendmsg+0x3cc/0x5f0 [18853.878030] sock_sendmsg+0xb4/0xd8 [18853.878043] ____sys_sendmsg+0x2f8/0x53c [18853.878058] ___sys_sendmsg+0xe8/0x150 [18853.878071] __sys_sendmsg+0xc4/0x1f4 [18853.878087] __arm64_compat_sys_sendmsg+0x88/0x9c [18853.878101] el0_svc_common+0x1b4/0x390 [18853.878115] do_el0_svc_compat+0x8c/0xdc [18853.878131] el0_svc_compat+0x10/0x1c [18853.878146] el0_sync_compat_handler+0xa8/0xcc [18853.878161] el0_sync_compat+0x188/0x1c0 [18853.878171] [18853.878183] Freed by task 10927: [18853.878200] kasan_save_stack+0x38/0x68 [18853.878215] kasan_set_track+0x28/0x3c [18853.878228] kasan_set_free_info+0x24/0x48 [18853.878244] __kasan_slab_free+0x11c/0x154 [18853.878259] kasan_slab_free+0x14/0x24 [18853.878273] slab_free_freelist_hook+0xac/0x1b0 [18853.878287] kfree+0x104/0x390 [18853.878402] sta_info_free+0x198/0x210 [mac80211] [18853.878515] __sta_info_destroy_part2+0x230/0x2d4 [mac80211] [18853.878628] __sta_info_flush+0x300/0x37c [mac80211] [18853.878740] ieee80211_set_disassoc+0x2cc/0xa7c [mac80211] [18853.878851] ieee80211_mgd_deauth+0x4a4/0x10a0 [mac80211] [18853.878962] ieee80211_deauth+0x20/0x2c [mac80211] [18853.879057] rdev_deauth+0x7c/0x438 [cfg80211] [18853.879150] cfg80211_mlme_deauth+0x274/0x414 [cfg80211] [18853.879243] cfg80211_mlme_down+0xe4/0x118 [cfg80211] [18853.879335] cfg80211_disconnect+0x218/0x2d8 [cfg80211] [18853.879427] __cfg80211_leave+0x17c/0x240 [cfg80211] [18853.879519] cfg80211_leave+0x3c/0x58 [cfg80211] [18853.879611] wiphy_suspend+0xdc/0x200 [cfg80211] [18853.879628] dpm_run_callback+0x58/0x408 [18853.879642] __device_suspend+0x4cc/0x864 [18853.879658] async_suspend+0x34/0xf4 [18853.879673] async_run_entry_fn+0xe0/0x37c [18853.879689] process_one_work+0x508/0xb98 [18853.879702] worker_thread+0x7f4/0xcd4 [18853.879717] kthread+0x2f8/0x3b8 [18853.879731] ret_from_fork+0x10/0x30 [18853.879741] [18853.879757] The buggy address belongs to the object at ffffffaf989a2000 [18853.879757] which belongs to the cache kmalloc-8k of size 8192 [18853.879774] The buggy address is located 312 bytes inside of [18853.879774] 8192-byte region [ffffffaf989a2000, ffffffaf989a4000) [18853.879787] The buggy address belongs to the page: [18853.879807] page:000000004bda2a59 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d89a0 [18853.879823] head:000000004bda2a59 order:3 compound_mapcount:0 compound_pincount:0 [18853.879839] flags: 0x8000000000010200(slab|head) [18853.879857] raw: 8000000000010200 ffffffffbc89e208 ffffffffb7fb5208 ffffffaec000cc80 [18853.879873] raw: 0000000000000000 0000000000010001 00000001ffffffff 0000000000000000 [18853.879885] page dumped because: kasan: bad access detected [18853.879896] [18853.879907] Memory state around the buggy address: [18853.879922] ffffffaf989a2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [18853.879935] ffffffaf989a2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [18853.879948] >ffffffaf989a2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [18853.879961] ^ [18853.879973] ffffffaf989a2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [18853.879986] ffffffaf989a2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [18853.879998] ================================================================== Cc: stable@vger.kernel.org Reported-by: Sean Wang <sean.wang@mediatek.com> Signed-off-by: Felix Fietkau <nbd@nbd.name>
diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -1303,7 +1303,7 @@ mt76_sta_add(struct mt76_dev *dev, struct ieee80211_vif *vif,
 			continue;
 
 		mtxq = (struct mt76_txq *)sta->txq[i]->drv_priv;
-		mtxq->wcid = wcid;
+		mtxq->wcid = wcid->idx;
 	}
 
 	ewma_signal_init(&wcid->rssi);
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -275,7 +275,7 @@ struct mt76_wcid {
 };
 
 struct mt76_txq {
-	struct mt76_wcid *wcid;
+	u16 wcid;
 
 	u16 agg_ssn;
 	bool send_bar;
diff --git a/drivers/net/wireless/mediatek/mt76/mt7603/main.c b/drivers/net/wireless/mediatek/mt76/mt7603/main.c
@@ -75,7 +75,7 @@ mt7603_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
 	mt7603_wtbl_init(dev, idx, mvif->idx, bc_addr);
 
 	mtxq = (struct mt76_txq *)vif->txq->drv_priv;
-	mtxq->wcid = &mvif->sta.wcid;
+	mtxq->wcid = idx;
 	rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);
 
 out:
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/main.c b/drivers/net/wireless/mediatek/mt76/mt7615/main.c
@@ -234,7 +234,7 @@ static int mt7615_add_interface(struct ieee80211_hw *hw,
 	rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);
 	if (vif->txq) {
 		mtxq = (struct mt76_txq *)vif->txq->drv_priv;
-		mtxq->wcid = &mvif->sta.wcid;
+		mtxq->wcid = idx;
 	}
 
 	ret = mt7615_mcu_add_dev_info(phy, vif, true);
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
@@ -292,7 +292,8 @@ mt76x02_vif_init(struct mt76x02_dev *dev, struct ieee80211_vif *vif,
 	mt76_packet_id_init(&mvif->group_wcid);
 
 	mtxq = (struct mt76_txq *)vif->txq->drv_priv;
-	mtxq->wcid = &mvif->group_wcid;
+	rcu_assign_pointer(dev->mt76.wcid[MT_VIF_WCID(idx)], &mvif->group_wcid);
+	mtxq->wcid = MT_VIF_WCID(idx);
 }
 
 int
@@ -345,6 +346,7 @@ void mt76x02_remove_interface(struct ieee80211_hw *hw,
 	struct mt76x02_vif *mvif = (struct mt76x02_vif *)vif->drv_priv;
 
 	dev->mt76.vif_mask &= ~BIT(mvif->idx);
+	rcu_assign_pointer(dev->mt76.wcid[mvif->group_wcid.idx], NULL);
 	mt76_packet_id_flush(&dev->mt76, &mvif->group_wcid);
 }
 EXPORT_SYMBOL_GPL(mt76x02_remove_interface);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/main.c b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
@@ -246,7 +246,7 @@ static int mt7915_add_interface(struct ieee80211_hw *hw,
 	rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);
 	if (vif->txq) {
 		mtxq = (struct mt76_txq *)vif->txq->drv_priv;
-		mtxq->wcid = &mvif->sta.wcid;
+		mtxq->wcid = idx;
 	}
 
 	if (vif->type != NL80211_IFTYPE_AP &&
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
@@ -330,7 +330,7 @@ static int mt7921_add_interface(struct ieee80211_hw *hw,
 	rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);
 	if (vif->txq) {
 		mtxq = (struct mt76_txq *)vif->txq->drv_priv;
-		mtxq->wcid = &mvif->sta.wcid;
+		mtxq->wcid = idx;
 	}
 
 out:
diff --git a/drivers/net/wireless/mediatek/mt76/tx.c b/drivers/net/wireless/mediatek/mt76/tx.c
@@ -436,12 +436,11 @@ mt76_txq_stopped(struct mt76_queue *q)
 
 static int
 mt76_txq_send_burst(struct mt76_phy *phy, struct mt76_queue *q,
-		    struct mt76_txq *mtxq)
+		    struct mt76_txq *mtxq, struct mt76_wcid *wcid)
 {
 	struct mt76_dev *dev = phy->dev;
 	struct ieee80211_txq *txq = mtxq_to_txq(mtxq);
 	enum mt76_txq_id qid = mt76_txq_get_qid(txq);
-	struct mt76_wcid *wcid = mtxq->wcid;
 	struct ieee80211_tx_info *info;
 	struct sk_buff *skb;
 	int n_frames = 1;
@@ -527,8 +526,8 @@ mt76_txq_schedule_list(struct mt76_phy *phy, enum mt76_txq_id qid)
 			break;
 
 		mtxq = (struct mt76_txq *)txq->drv_priv;
-		wcid = mtxq->wcid;
-		if (wcid && test_bit(MT_WCID_FLAG_PS, &wcid->flags))
+		wcid = rcu_dereference(dev->wcid[mtxq->wcid]);
+		if (!wcid || test_bit(MT_WCID_FLAG_PS, &wcid->flags))
 			continue;
 
 		if (mtxq->send_bar && mtxq->aggr) {
@@ -543,7 +542,7 @@ mt76_txq_schedule_list(struct mt76_phy *phy, enum mt76_txq_id qid)
 		}
 
 		if (!mt76_txq_stopped(q))
-			n_frames = mt76_txq_send_burst(phy, q, mtxq);
+			n_frames = mt76_txq_send_burst(phy, q, mtxq, wcid);
 
 		ieee80211_return_txq(phy->hw, txq, false);
 

Original file line number	Diff line number	Diff line change
`@@ -1303,7 +1303,7 @@ mt76_sta_add(struct mt76_dev dev, struct ieee80211_vif vif,`
`1303`	`1303`	`continue;`
`1304`	`1304`
`1305`	`1305`	`mtxq = (struct mt76_txq *)sta->txq[i]->drv_priv;`
`1306`		`- mtxq->wcid = wcid;`
	`1306`	`+ mtxq->wcid = wcid->idx;`
`1307`	`1307`	`}`
`1308`	`1308`
`1309`	`1309`	`ewma_signal_init(&wcid->rssi);`
Original file line number	Diff line number	Diff line change
`@@ -234,7 +234,7 @@ static int mt7615_add_interface(struct ieee80211_hw *hw,`
`234`	`234`	`rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);`
`235`	`235`	`if (vif->txq) {`
`236`	`236`	`mtxq = (struct mt76_txq *)vif->txq->drv_priv;`
`237`		`- mtxq->wcid = &mvif->sta.wcid;`
	`237`	`+ mtxq->wcid = idx;`
`238`	`238`	`}`
`239`	`239`
`240`	`240`	`ret = mt7615_mcu_add_dev_info(phy, vif, true);`
Original file line number	Diff line number	Diff line change
`@@ -292,7 +292,8 @@ mt76x02_vif_init(struct mt76x02_dev dev, struct ieee80211_vif vif,`
`292`	`292`	`mt76_packet_id_init(&mvif->group_wcid);`
`293`	`293`
`294`	`294`	`mtxq = (struct mt76_txq *)vif->txq->drv_priv;`
`295`		`- mtxq->wcid = &mvif->group_wcid;`
	`295`	`+ rcu_assign_pointer(dev->mt76.wcid[MT_VIF_WCID(idx)], &mvif->group_wcid);`
	`296`	`+ mtxq->wcid = MT_VIF_WCID(idx);`
`296`	`297`	`}`
`297`	`298`
`298`	`299`	`int`
`@@ -345,6 +346,7 @@ void mt76x02_remove_interface(struct ieee80211_hw *hw,`
`345`	`346`	`struct mt76x02_vif mvif = (struct mt76x02_vif )vif->drv_priv;`
`346`	`347`
`347`	`348`	`dev->mt76.vif_mask &= ~BIT(mvif->idx);`
	`349`	`+ rcu_assign_pointer(dev->mt76.wcid[mvif->group_wcid.idx], NULL);`
`348`	`350`	`mt76_packet_id_flush(&dev->mt76, &mvif->group_wcid);`
`349`	`351`	`}`
`350`	`352`	`EXPORT_SYMBOL_GPL(mt76x02_remove_interface);`
Original file line number	Diff line number	Diff line change
`@@ -246,7 +246,7 @@ static int mt7915_add_interface(struct ieee80211_hw *hw,`
`246`	`246`	`rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);`
`247`	`247`	`if (vif->txq) {`
`248`	`248`	`mtxq = (struct mt76_txq *)vif->txq->drv_priv;`
`249`		`- mtxq->wcid = &mvif->sta.wcid;`
	`249`	`+ mtxq->wcid = idx;`
`250`	`250`	`}`
`251`	`251`
`252`	`252`	`if (vif->type != NL80211_IFTYPE_AP &&`
Original file line number	Diff line number	Diff line change
`@@ -330,7 +330,7 @@ static int mt7921_add_interface(struct ieee80211_hw *hw,`
`330`	`330`	`rcu_assign_pointer(dev->mt76.wcid[idx], &mvif->sta.wcid);`
`331`	`331`	`if (vif->txq) {`
`332`	`332`	`mtxq = (struct mt76_txq *)vif->txq->drv_priv;`
`333`		`- mtxq->wcid = &mvif->sta.wcid;`
	`333`	`+ mtxq->wcid = idx;`
`334`	`334`	`}`
`335`	`335`
`336`	`336`	`out:`