[PATCH ath-next] wifi: ath11k: hold txmgmt_idr_lock while freeing pending mgmt frames

[Changyul Lee <lcy8047@gmail.com>]

ath11k_mac_vif_txmgmt_cleanup() and ath11k_mac_tx_mgmt_pending_free()
walk ar->txmgmt_idr without txmgmt_idr_lock. A WMI management TX
completion can meanwhile remove an entry and pass its skb to mac80211,
which frees it. ath11k_mac_vif_txmgmt_cleanup() then reads skb_cb->vif
from the freed skb, and both walks can read an IDR node that was freed
after an RCU grace period.

Hold txmgmt_idr_lock over both walks and make ath11k_mac_tx_mgmt_free()
expect it to be held.

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Suggested-by: Rameshkumar Sundaram <rameshkumar.sundaram@oss.qualcomm.com>
Signed-off-by: Changyul Lee <lcy8047@gmail.com>
---
Found with a static analysis tool we are developing.

This is the follow-up for the skb use-after-free that was left out of
the "wifi: ath: avoid IDR mutation while iterating" series.

Compile-tested only, with x86_64_defconfig plus ATH11K_PCI and W=1.

 drivers/net/wireless/ath/ath11k/mac.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index 1a237adaa37d..ef60811fcf54 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -6151,10 +6151,9 @@ static void ath11k_mac_tx_mgmt_free(struct ath11k *ar, int buf_id)
 	struct sk_buff *msdu;
 	struct ieee80211_tx_info *info;
 
-	spin_lock_bh(&ar->txmgmt_idr_lock);
-	msdu = idr_remove(&ar->txmgmt_idr, buf_id);
-	spin_unlock_bh(&ar->txmgmt_idr_lock);
+	lockdep_assert_held(&ar->txmgmt_idr_lock);
 
+	msdu = idr_remove(&ar->txmgmt_idr, buf_id);
 	if (!msdu)
 		return;
 
@@ -6172,8 +6171,10 @@ void ath11k_mac_tx_mgmt_pending_free(struct ath11k *ar)
 	struct sk_buff *msdu;
 	int buf_id;
 
+	spin_lock_bh(&ar->txmgmt_idr_lock);
 	idr_for_each_entry(&ar->txmgmt_idr, msdu, buf_id)
 		ath11k_mac_tx_mgmt_free(ar, buf_id);
+	spin_unlock_bh(&ar->txmgmt_idr_lock);
 }
 
 static void ath11k_mac_vif_txmgmt_cleanup(struct ath11k *ar,
@@ -6183,11 +6184,13 @@ static void ath11k_mac_vif_txmgmt_cleanup(struct ath11k *ar,
 	struct sk_buff *skb;
 	int buf_id;
 
+	spin_lock_bh(&ar->txmgmt_idr_lock);
 	idr_for_each_entry(&ar->txmgmt_idr, skb, buf_id) {
 		skb_cb = ATH11K_SKB_CB(skb);
 		if (skb_cb->vif == vif)
 			ath11k_mac_tx_mgmt_free(ar, buf_id);
 	}
+	spin_unlock_bh(&ar->txmgmt_idr_lock);
 }
 
 static int ath11k_mac_mgmt_tx_wmi(struct ath11k *ar, struct ath11k_vif *arvif,

base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb
-- 
2.43.0