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.

As this is forbidden behavior, we add a check for 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 report an error that the device is misbehaving, and ignore the
packet.

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 <redacted>
---

v1 -> v2:
- Added more comments to explain the reasoning behind the new check, and
a bt_dev_err message upon detecting the invalid event. As suggested by
Marcel Holtmann.

net/bluetooth/hci_event.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

I shortened the error message and then applied your patch to bluetooth-next tree.

Regards

Marcel

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