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authorThadeu Lima de Souza Cascardo <cascardo@canonical.com>2021-04-13 13:21:03 -0300
committerMarcel Holtmann <marcel@holtmann.org>2021-06-26 07:12:25 +0200
commit3cfdf8fcaafa62a4123f92eb0f4a72650da3a479 (patch)
tree13b754f68b1f05811bdc90ac841064c849d94104 /net/bluetooth
parent44e936d7459cac598d9fe0b6d23cc9d12b648d5e (diff)
Bluetooth: cmtp: fix file refcount when cmtp_attach_device fails
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>
Diffstat (limited to 'net/bluetooth')
-rw-r--r--net/bluetooth/cmtp/core.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c
index 07cfa3249f83..0a2d78e811cf 100644
--- a/net/bluetooth/cmtp/core.c
+++ b/net/bluetooth/cmtp/core.c
@@ -392,6 +392,11 @@ 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);