Re: [PATCH] net: bluetooth: cmtp: fix file refcount when cmtp_attach_device fails

Hi Thadeu,

When cmtp_attach_device fails, cmtp_add_connection returns the error value
which leads to the caller to doing fput through sockfd_put. But
cmtp_session kthread, which is stopped in this path will also call fput,
leading to a potential refcount underflow or a use-after-free.

Add a refcount before we signal the kthread to stop. The kthread will try
to grab the cmtp_session_sem mutex before doing the fput, which is held
when get_file is called, so there should be no races there.

Reported-by: Ryota Shiga
Signed-off-by: Thadeu Lima de Souza Cascardo <redacted>
---
net/bluetooth/cmtp/core.c | 5 +++++
1 file changed, 5 insertions(+)

Patch has been applied to bluetooth-next tree.

Regards

Marcel