linux-kernel - [PATCH v1] Bluetooth: hci_qca: Fix double free during SSR timeout

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Date:   Thu,  4 Jun 2020 19:27:12 +0530
From:   Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
To:     marcel@...tmann.org, johan.hedberg@...il.com
Cc:     mka@...omium.org, linux-kernel@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, robh@...nel.org,
        hemantg@...eaurora.org, linux-arm-msm@...r.kernel.org,
        bgodavar@...eaurora.org, tientzu@...omium.org,
        seanpaul@...omium.org, rjliao@...eaurora.org, yshavit@...gle.com,
        Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
Subject: [PATCH v1] Bluetooth: hci_qca: Fix double free during SSR timeout

Due to race conditions between qca_hw_error and qca_controller_memdump
during SSR timeout,the same pointer is freed twice. Which results to
double free error. Now a lock is acquired while SSR state moved to timeout.

Signed-off-by: Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
---
 drivers/bluetooth/hci_qca.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 836949d..9110775 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -983,8 +983,11 @@ static void qca_controller_memdump(struct work_struct *work)
 	while ((skb = skb_dequeue(&qca->rx_memdump_q))) {
 
 		mutex_lock(&qca->hci_memdump_lock);
-		/* Skip processing the received packets if timeout detected. */
-		if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
+		/* Skip processing the received packets if timeout detected
+		 * or memdump collection completed.
+		 */
+		if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT ||
+		    qca->memdump_state == QCA_MEMDUMP_COLLECTED) {
 			mutex_unlock(&qca->hci_memdump_lock);
 			return;
 		}
@@ -1485,7 +1488,7 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
 {
 	struct hci_uart *hu = hci_get_drvdata(hdev);
 	struct qca_data *qca = hu->priv;
-	struct qca_memdump_data *qca_memdump = qca->qca_memdump;
+	struct qca_memdump_data *qca_memdump = NULL;
 	char *memdump_buf = NULL;
 
 	set_bit(QCA_HW_ERROR_EVENT, &qca->flags);
@@ -1509,9 +1512,10 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
 		qca_wait_for_dump_collection(hdev);
 	}
 
+	mutex_lock(&qca->hci_memdump_lock);
 	if (qca->memdump_state != QCA_MEMDUMP_COLLECTED) {
 		bt_dev_err(hu->hdev, "clearing allocated memory due to memdump timeout");
-		mutex_lock(&qca->hci_memdump_lock);
+		qca_memdump = qca->qca_memdump;
 		if (qca_memdump)
 			memdump_buf = qca_memdump->memdump_buf_head;
 		vfree(memdump_buf);
@@ -1520,8 +1524,13 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
 		qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
 		cancel_delayed_work(&qca->ctrl_memdump_timeout);
 		skb_queue_purge(&qca->rx_memdump_q);
-		mutex_unlock(&qca->hci_memdump_lock);
+	}
+	mutex_unlock(&qca->hci_memdump_lock);
+
+	if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT ||
+	    qca->memdump_state == QCA_MEMDUMP_COLLECTED) {
 		cancel_work_sync(&qca->ctrl_memdump_evt);
+		skb_queue_purge(&qca->rx_memdump_q);
 	}
 
 	clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
-- 
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