Bluetooth: cmtp: fix file refcount when cmtp_attach_device fails

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commit 8da3a0b87f4f1c3a3bbc4bfb78cf68476e97d183 upstream.

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 <cascardo@canonical.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Thadeu Lima de Souza Cascardo 2021-04-13 13:21:03 -03:00 • committed by Greg Kroah-Hartman

parent 635ac38b36

commit 1b364f8ede

1 changed files with 5 additions and 0 deletions

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net/bluetooth/cmtp/core.c

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