Re: [PATCH v1] Bluetooth: hci_qca: Fix double free during SSR timeout

[bgodavar]

On 2020-06-04 19:27, Venkata Lakshmi Narayana Gubba wrote:

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 <gubba...@codeaurora.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);

Reviewed-by: Balakrishna Godavarthi <bgoda...@codeaurora.org>