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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id j4sm3658711oom.11.2021.04.05.17.27.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Apr 2021 17:27:16 -0700 (PDT) Subject: Re: [PATCH 5.10 047/126] ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr() To: Pavel Machek , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Kalle Valo , Sasha Levin , Shuah Khan References: <20210405085031.040238881@linuxfoundation.org> <20210405085032.596054465@linuxfoundation.org> <20210405153452.GC32232@amd> From: Shuah Khan Message-ID: <3ad53312-6349-3663-103e-8636bd53d117@linuxfoundation.org> Date: Mon, 5 Apr 2021 18:27:15 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210405153452.GC32232@amd> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/5/21 9:34 AM, Pavel Machek wrote: > Hi! > >> 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. > > It does that. But is also does the unlock even if it did not take the > lock: > There is only one path after it takes the lock. >> +++ 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(); Takes the lock here: >> 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; Releases it if something fails >> } >> 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; >> } >> + falls through here. >> +exit: >> + rcu_read_unlock(); >> kfree(tb); >> } > > The switch only takes the lock in 3 branches, but it is released > unconditionally at the end. > I don't see any other switch cases. However, default is missing: It could be done this way perhaps: (simpler than what you proposed) diff --git a/drivers/net/wireless/ath/ath10k/wmi-tlv.c b/drivers/net/wireless/ath/ath10k/wmi-tlv.c index d97b33f789e4..7efbe03fbca8 100644 --- a/drivers/net/wireless/ath/ath10k/wmi-tlv.c +++ b/drivers/net/wireless/ath/ath10k/wmi-tlv.c @@ -592,6 +592,9 @@ static void ath10k_wmi_event_tdls_peer(struct ath10k *ar, struct sk_buff *skb) GFP_ATOMIC ); break; + default: + kfree(tb); + return; } exit: thanks, -- Shuah