[PATCH 5.17 711/772] mt76: fix use-after-free by removing a non-RCU wcid pointer

Greg Kroah-Hartman
2022-06-07T21:46:51Z

From: Felix Fietkau <nbd@nbd.name>

commit 51fb1278aa57ae0fc54adaa786e1965362bed4fb upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/wireless/mediatek/mt76/mac80211.c | 2 +-
drivers/net/wireless/mediatek/mt76/mt76.h | 2 +-
drivers/net/wireless/mediatek/mt76/mt7603/main.c | 2 +-
drivers/net/wireless/mediatek/mt76/mt7615/main.c | 2 +-
drivers/net/wireless/mediatek/mt76/mt76x02_util.c | 4 +++-
drivers/net/wireless/mediatek/mt76/mt7915/main.c | 2 +-
drivers/net/wireless/mediatek/mt76/mt7921/main.c | 2 +-
drivers/net/wireless/mediatek/mt76/tx.c | 9 ++++-----
8 files changed, 13 insertions(+), 12 deletions(-)

--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -1266,7 +1266,7 @@ mt76_sta_add(struct mt76_dev *dev, struc
continue;

mtxq = (struct mt76_txq *)sta->txq[i]->drv_priv;
- mtxq->wcid = wcid;
+ mtxq->wcid = wcid->idx;
}

ewma_signal_init(&wcid->rssi);
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -267,7 +267,7 @@ struct mt76_wcid {
};

struct mt76_txq {
- struct mt76_wcid *wcid;
+ u16 wcid;

u16 agg_ssn;
bool send_bar;
--- 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
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:
--- 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 i
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);
--- 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
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 iee
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);
--- a/drivers/net/wireless/mediatek/mt76/mt7915/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
@@ -245,7 +245,7 @@ static int mt7915_add_interface(struct i
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 &&
--- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
@@ -329,7 +329,7 @@ static int mt7921_add_interface(struct i
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:
--- 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;
@@ -521,8 +520,8 @@ mt76_txq_schedule_list(struct mt76_phy *
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;

spin_lock_bh(&q->lock);
@@ -541,7 +540,7 @@ mt76_txq_schedule_list(struct mt76_phy *
}

if (!mt76_txq_stopped(q))
- n_frames = mt76_txq_send_burst(phy, q, mtxq);
+ n_frames = mt76_txq_send_burst(phy, q, mtxq, wcid);

spin_unlock_bh(&q->lock);