linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] Bluetooth: skip invalid hci_sync_conn_complete_evt
@ 2021-07-21 10:17 Desmond Cheong Zhi Xi
  2021-07-22 14:39 ` Marcel Holtmann
  0 siblings, 1 reply; 3+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-07-21 10:17 UTC (permalink / raw)
  To: marcel, johan.hedberg, luiz.dentz, davem, kuba
  Cc: Desmond Cheong Zhi Xi, linux-bluetooth, netdev, linux-kernel,
	skhan, gregkh, linux-kernel-mentees, syzbot+66264bf2fd0476be7e6c

Syzbot reported a corrupted list in kobject_add_internal [1]. This
happens when multiple HCI_EV_SYNC_CONN_COMPLETE event packets with
status 0 are sent for the same HCI connection. This causes us to
register the device more than once which corrupts the kset list.

To fix this, in hci_sync_conn_complete_evt, we check whether we're
trying to process the same HCI_EV_SYNC_CONN_COMPLETE event multiple
times for one connection. If that's the case, the event is invalid, so
we skip further processing and exit.

Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c [1]
Reported-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
Tested-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
---
 net/bluetooth/hci_event.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 016b2999f219..091a92338492 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4373,6 +4373,8 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,
 
 	switch (ev->status) {
 	case 0x00:
+		if (conn->state == BT_CONNECTED)
+			goto unlock;  /* Already connected, event not valid */
 		conn->handle = __le16_to_cpu(ev->handle);
 		conn->state  = BT_CONNECTED;
 		conn->type   = ev->link_type;
-- 
2.25.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] Bluetooth: skip invalid hci_sync_conn_complete_evt
  2021-07-21 10:17 [PATCH] Bluetooth: skip invalid hci_sync_conn_complete_evt Desmond Cheong Zhi Xi
@ 2021-07-22 14:39 ` Marcel Holtmann
  2021-07-28  6:47   ` Desmond Cheong Zhi Xi
  0 siblings, 1 reply; 3+ messages in thread
From: Marcel Holtmann @ 2021-07-22 14:39 UTC (permalink / raw)
  To: Desmond Cheong Zhi Xi
  Cc: Johan Hedberg, Luiz Augusto von Dentz, David S. Miller,
	Jakub Kicinski, linux-bluetooth, open list:NETWORKING [GENERAL],
	open list, skhan, gregkh, linux-kernel-mentees,
	syzbot+66264bf2fd0476be7e6c

Hi Desmond,

> Syzbot reported a corrupted list in kobject_add_internal [1]. This
> happens when multiple HCI_EV_SYNC_CONN_COMPLETE event packets with
> status 0 are sent for the same HCI connection. This causes us to
> register the device more than once which corrupts the kset list.

and that is actually forbidden by the spec. So we need to complain loudly that such a device is misbehaving.

> To fix this, in hci_sync_conn_complete_evt, we check whether we're
> trying to process the same HCI_EV_SYNC_CONN_COMPLETE event multiple
> times for one connection. If that's the case, the event is invalid, so
> we skip further processing and exit.
> 
> Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c [1]
> Reported-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
> Tested-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
> Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
> ---
> net/bluetooth/hci_event.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 016b2999f219..091a92338492 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -4373,6 +4373,8 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,
> 
> 	switch (ev->status) {
> 	case 0x00:
> +		if (conn->state == BT_CONNECTED)
> +			goto unlock;  /* Already connected, event not valid */

The comment has go above and be a lot more details since this is not expected behavior from valid hardware and we should add a bt_dev_err as well.

> 		conn->handle = __le16_to_cpu(ev->handle);
> 		conn->state  = BT_CONNECTED;
> 		conn->type   = ev->link_type;

Regards

Marcel


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] Bluetooth: skip invalid hci_sync_conn_complete_evt
  2021-07-22 14:39 ` Marcel Holtmann
@ 2021-07-28  6:47   ` Desmond Cheong Zhi Xi
  0 siblings, 0 replies; 3+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-07-28  6:47 UTC (permalink / raw)
  To: Marcel Holtmann
  Cc: Johan Hedberg, Luiz Augusto von Dentz, David S. Miller,
	Jakub Kicinski, linux-bluetooth, open list:NETWORKING [GENERAL],
	open list, skhan, gregkh, linux-kernel-mentees,
	syzbot+66264bf2fd0476be7e6c

On 22/7/21 10:39 pm, Marcel Holtmann wrote:
> Hi Desmond,
> 
>> Syzbot reported a corrupted list in kobject_add_internal [1]. This
>> happens when multiple HCI_EV_SYNC_CONN_COMPLETE event packets with
>> status 0 are sent for the same HCI connection. This causes us to
>> register the device more than once which corrupts the kset list.
> 
> and that is actually forbidden by the spec. So we need to complain loudly that such a device is misbehaving.
> 
>> To fix this, in hci_sync_conn_complete_evt, we check whether we're
>> trying to process the same HCI_EV_SYNC_CONN_COMPLETE event multiple
>> times for one connection. If that's the case, the event is invalid, so
>> we skip further processing and exit.
>>
>> Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c [1]
>> Reported-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
>> Tested-by: syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com
>> Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
>> ---
>> net/bluetooth/hci_event.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
>> index 016b2999f219..091a92338492 100644
>> --- a/net/bluetooth/hci_event.c
>> +++ b/net/bluetooth/hci_event.c
>> @@ -4373,6 +4373,8 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,
>>
>> 	switch (ev->status) {
>> 	case 0x00:
>> +		if (conn->state == BT_CONNECTED)
>> +			goto unlock;  /* Already connected, event not valid */
> 
> The comment has go above and be a lot more details since this is not expected behavior from valid hardware and we should add a bt_dev_err as well.
> 

Hi Marcel,

Apologies for the delayed response.

Thanks for the feedback, I'll add more elaboration for the new check and 
add a bt_dev_err in a v2 patch.

>> 		conn->handle = __le16_to_cpu(ev->handle);
>> 		conn->state  = BT_CONNECTED;
>> 		conn->type   = ev->link_type;
> 
> Regards
> 
> Marcel
> 


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-07-28  6:47 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-21 10:17 [PATCH] Bluetooth: skip invalid hci_sync_conn_complete_evt Desmond Cheong Zhi Xi
2021-07-22 14:39 ` Marcel Holtmann
2021-07-28  6:47   ` Desmond Cheong Zhi Xi

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).