ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
the resulting pointer is only valid under RCU lock as well.
Fix ath_tx_process_buffer() to hold RCU read lock before it calls
ieee80211_find_sta_by_ifaddr() and release it when the resulting
pointer is no longer needed.
This problem was found while reviewing code to debug RCU warn from
ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
RCU read lock.
Signed-off-by: Shuah Khan <[email protected]>
---
- Note: This patch is compile tested. I don't have access to
hardware.
drivers/net/wireless/ath/ath9k/xmit.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index e60d4737fc6e..1d36aae3f7b6 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -701,6 +701,9 @@ static void ath_tx_process_buffer(struct ath_softc *sc, struct ath_txq *txq,
ts->ts_rateindex);
hdr = (struct ieee80211_hdr *) bf->bf_mpdu->data;
+
+ rcu_read_lock();
+
sta = ieee80211_find_sta_by_ifaddr(hw, hdr->addr1, hdr->addr2);
if (sta) {
struct ath_node *an = (struct ath_node *)sta->drv_priv;
@@ -725,6 +728,8 @@ static void ath_tx_process_buffer(struct ath_softc *sc, struct ath_txq *txq,
if (!flush)
ath_txq_schedule(sc, txq);
+
+ rcu_read_unlock();
}
static bool ath_lookup_legacy(struct ath_buf *bf)
--
2.27.0
ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
the resulting pointer is only valid under RCU lock as well.
Fix mt76_check_sta() to hold RCU read lock before it calls
ieee80211_find_sta_by_ifaddr() and release it when the resulting
pointer is no longer needed.
This problem was found while reviewing code to debug RCU warn from
ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
RCU read lock.
Signed-off-by: Shuah Khan <[email protected]>
---
- Note: This patch is compile tested. I don't have access to
hardware.
drivers/net/wireless/mediatek/mt76/mac80211.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index a840396f2c74..3c732da2a53f 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -867,6 +867,9 @@ mt76_check_sta(struct mt76_dev *dev, struct sk_buff *skb)
bool ps;
hw = mt76_phy_hw(dev, status->ext_phy);
+
+ rcu_read_lock();
+
if (ieee80211_is_pspoll(hdr->frame_control) && !wcid) {
sta = ieee80211_find_sta_by_ifaddr(hw, hdr->addr2, NULL);
if (sta)
@@ -876,7 +879,7 @@ mt76_check_sta(struct mt76_dev *dev, struct sk_buff *skb)
mt76_airtime_check(dev, skb);
if (!wcid || !wcid->sta)
- return;
+ goto exit;
sta = container_of((void *)wcid, struct ieee80211_sta, drv_priv);
@@ -886,17 +889,17 @@ mt76_check_sta(struct mt76_dev *dev, struct sk_buff *skb)
wcid->inactive_count = 0;
if (!test_bit(MT_WCID_FLAG_CHECK_PS, &wcid->flags))
- return;
+ goto exit;
if (ieee80211_is_pspoll(hdr->frame_control)) {
ieee80211_sta_pspoll(sta);
- return;
+ goto exit;
}
if (ieee80211_has_morefrags(hdr->frame_control) ||
!(ieee80211_is_mgmt(hdr->frame_control) ||
ieee80211_is_data(hdr->frame_control)))
- return;
+ goto exit;
ps = ieee80211_has_pm(hdr->frame_control);
@@ -905,7 +908,7 @@ mt76_check_sta(struct mt76_dev *dev, struct sk_buff *skb)
ieee80211_sta_uapsd_trigger(sta, status->tid);
if (!!test_bit(MT_WCID_FLAG_PS, &wcid->flags) == ps)
- return;
+ goto exit;
if (ps)
set_bit(MT_WCID_FLAG_PS, &wcid->flags);
@@ -914,6 +917,9 @@ mt76_check_sta(struct mt76_dev *dev, struct sk_buff *skb)
dev->drv->sta_ps(dev, sta, ps);
ieee80211_sta_ps_transition(sta, ps);
+
+exit:
+ rcu_read_unlock();
}
void mt76_rx_complete(struct mt76_dev *dev, struct sk_buff_head *frames,
--
2.27.0
On 2021-02-12 03:13, Shuah Khan wrote:
> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
> the resulting pointer is only valid under RCU lock as well.
>
> Fix mt76_check_sta() to hold RCU read lock before it calls
> ieee80211_find_sta_by_ifaddr() and release it when the resulting
> pointer is no longer needed.
>
> This problem was found while reviewing code to debug RCU warn from
> ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
> of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
> RCU read lock.
>
> Signed-off-by: Shuah Khan <[email protected]>
If I'm not mistaken, this patch is unnecessary. mt76_check_sta is only
called from mt76_rx_poll_complete, which itself is only called under RCU
lock.
- Felix
On 2021-02-12 03:13, Shuah Khan wrote:
> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
> the resulting pointer is only valid under RCU lock as well.
>
> Fix ath_tx_process_buffer() to hold RCU read lock before it calls
> ieee80211_find_sta_by_ifaddr() and release it when the resulting
> pointer is no longer needed.
>
> This problem was found while reviewing code to debug RCU warn from
> ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
> of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
> RCU read lock.
>
> Signed-off-by: Shuah Khan <[email protected]>
This patch seems unnecessary as well. All callers of
ath_tx_process_buffer seem to hold the RCU read lock already.
- Felix
On 2/11/21 10:36 PM, Felix Fietkau wrote:
>
> On 2021-02-12 03:13, Shuah Khan wrote:
>> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
>> the resulting pointer is only valid under RCU lock as well.
>>
>> Fix mt76_check_sta() to hold RCU read lock before it calls
>> ieee80211_find_sta_by_ifaddr() and release it when the resulting
>> pointer is no longer needed.
>>
>> This problem was found while reviewing code to debug RCU warn from
>> ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
>> of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
>> RCU read lock.
>>
>> Signed-off-by: Shuah Khan <[email protected]>
> If I'm not mistaken, this patch is unnecessary. mt76_check_sta is only
> called from mt76_rx_poll_complete, which itself is only called under RCU
> lock.
>
Yes. You are right. I checked the caller of this routine and didn't
go further up. :)
thanks,
-- Shuah