2021-02-10 21:25:08

by Shuah Khan

Subject: [PATCH v2] ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

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 ath10k_wmi_tlv_op_pull_peer_stats_info() to hold RCU 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().

Link: https://lore.kernel.org/linux-wireless/[email protected]/
Signed-off-by: Shuah Khan <[email protected]>
---
Changes since v1:
- v1 also included fix to ath10k_wmi_tlv_parse_peer_stats_info()
RCU wrn which was already fixed. v2 drops that and fixes just
ath10k_wmi_event_tdls_peer()

drivers/net/wireless/ath/ath10k/wmi-tlv.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/wmi-tlv.c b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
index bfdd017f1405..d97b33f789e4 100644
--- a/drivers/net/wireless/ath/ath10k/wmi-tlv.c
+++ b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
@@ -576,13 +576,13 @@ static void ath10k_wmi_event_tdls_peer(struct ath10k *ar, struct sk_buff *skb)
case WMI_TDLS_TEARDOWN_REASON_TX:
case WMI_TDLS_TEARDOWN_REASON_RSSI:
case WMI_TDLS_TEARDOWN_REASON_PTR_TIMEOUT:
+ rcu_read_lock();
station = ieee80211_find_sta_by_ifaddr(ar->hw,
ev->peer_macaddr.addr,
NULL);
if (!station) {
ath10k_warn(ar, "did not find station from tdls peer event");
- kfree(tb);
- return;
+ goto exit;
}
arvif = ath10k_get_arvif(ar, __le32_to_cpu(ev->vdev_id));
ieee80211_tdls_oper_request(
@@ -593,6 +593,9 @@ static void ath10k_wmi_event_tdls_peer(struct ath10k *ar, struct sk_buff *skb)
);
break;
}
+
+exit:
+ rcu_read_unlock();
kfree(tb);
}

--
2.27.0

2021-02-11 18:30:25

by Kalle Valo

Subject: Re: [PATCH v2] ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

Shuah Khan <[email protected]> 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 ath10k_wmi_tlv_op_pull_peer_stats_info() to hold RCU 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().
>
> Link: https://lore.kernel.org/linux-wireless/[email protected]/
> Signed-off-by: Shuah Khan <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>

Patch applied to ath-next branch of ath.git, thanks.

09078368d516 ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches