| Message ID | 1591279032-7527-1-git-send-email-gubbaven@codeaurora.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] Bluetooth: hci_qca: Fix double free during SSR timeout | expand |
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 <gubbaven@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 <bgodavar@codeaurora.org>
Hi Abhishek, On 2020-06-05 10:23, Abhishek Pandit-Subedi wrote: > Hi, > > On Thu, Jun 4, 2020 at 6:59 AM Venkata Lakshmi Narayana Gubba > <gubbaven@codeaurora.org> 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. > suggestion: Change "which results to double free error" to "This > results in a double free." > suggestion: Change "while SSR state moved to timeout" to "when SSR > state is changed to timeout" > [Venkata]: Sure will update in next patchset. >> >> Signed-off-by: Venkata Lakshmi Narayana Gubba >> <gubbaven@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); > > This section of code looks a bit unclear because it's only partially > in an if statement. Suggestion: > if (qca->qca_memdump) { > vfree(qca->qca_memdump->memdump_buf_head); > kfree(qca->qca_memdump); > qca->qca_memdump = NULL; > } > [Venkata]: Sure will update in next patchset. >> @@ -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); >> } > > Earlier in the function, you call qca_wait_for_dump_collection for > [Idle, Collecting] so the state should be either [Timeout, Collected] > at this branch. So, you can remove the `cancel_delayed_work` and > `skb_queue_purge` from above and just leave it only in the bottom > branch. Currently you're duplicating these calls unnecessarily. > > I don't know if we discussed this in an earlier review but I noticed > that `qca_wait_for_dump_collection` doesn't actually pay attention to > the return value of `wait_on_bit_timeout`. I don't have context for > the order of calls anymore but is there a possibility for that timeout > to complete before `qca_memdump_timeout` is called? In that case, you > should probably set the state to timeout in > `qca_wait_for_dump_collection` as well. > [Venkata]: I see only skb_queue_purge is getting duplicated and will update in next patchset. But cancel_delayed_work is for qca->ctrl_memdump_timeout and cancel_work_sync is for qca->ctrl_memdump_evt.So these calls are not getting duplicated. If timeout happens in qca_wait_for_dump_collection, we are setting state to timeout in subsequent if block which is if (qca->memdump_state != QCA_MEMDUMP_COLLECTED). >> >> clear_bit(QCA_HW_ERROR_EVENT, &qca->flags); >> -- >> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a >> member >> of Code Aurora Forum, hosted by The Linux Foundation >> Regards, Lakshmi Narayana.
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);
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@codeaurora.org> --- drivers/bluetooth/hci_qca.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)