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@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
---
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.
