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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id c2sm3480594ilk.32.2021.02.11.18.13.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Feb 2021 18:13:13 -0800 (PST) From: Shuah Khan To: nbd@nbd.name, lorenzo.bianconi83@gmail.com, ryder.lee@mediatek.com, kvalo@codeaurora.org, davem@davemloft.net, kuba@kernel.org, matthias.bgg@gmail.com Cc: Shuah Khan , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] mt76: hold RCU lock when calling ieee80211_find_sta_by_ifaddr() Date: Thu, 11 Feb 2021 19:13:06 -0700 Message-Id: <20210212021312.40486-1-skhan@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <1cfa036227cfa9fdd04316c01e1d754f13a70d9e.1613090339.git.skhan@linuxfoundation.org> References: <1cfa036227cfa9fdd04316c01e1d754f13a70d9e.1613090339.git.skhan@linuxfoundation.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- - 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