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| author | Thadeu Lima de Souza Cascardo <cascardo@canonical.com> | 2021-04-13 13:21:03 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-03 08:38:08 +0200 |
| commit | f8be26b9950710fe50fb45358df5bd01ad18efb7 (patch) | |
| tree | 53a7489ab014ff1342d5087c9f4e7f14d52819b6 /net | |
| parent | c4b70e0d2acd019800b72b954012ed2fc3c4fef6 (diff) | |
| download | linux-f8be26b9950710fe50fb45358df5bd01ad18efb7.tar.gz linux-f8be26b9950710fe50fb45358df5bd01ad18efb7.tar.bz2 linux-f8be26b9950710fe50fb45358df5bd01ad18efb7.zip | |
Bluetooth: cmtp: fix file refcount when cmtp_attach_device fails
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/bluetooth/cmtp/core.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c index 7f26a5a19ff6..9873684a9d8f 100644 --- a/net/bluetooth/cmtp/core.c +++ b/net/bluetooth/cmtp/core.c @@ -391,6 +391,11 @@ int cmtp_add_connection(struct cmtp_connadd_req *req, struct socket *sock) if (!(session->flags & BIT(CMTP_LOOPBACK))) { err = cmtp_attach_device(session); if (err < 0) { + /* Caller will call fput in case of failure, and so + * will cmtp_session kthread. + */ + get_file(session->sock->file); + atomic_inc(&session->terminate); wake_up_interruptible(sk_sleep(session->sock->sk)); up_write(&cmtp_session_sem); |