ksmbd: fix racy issue while destroying session on multichannel

[ Upstream commit af7c39d9 ]

After multi-channel connection with windows, Several channels of
session are connected. Among them, if there is a problem in one channel,
Windows connects again after disconnecting the channel. In this process,
the session is released and a kernel oop can occurs while processing
requests to other channels. When the channel is disconnected, if other
channels still exist in the session after deleting the channel from
the channel list in the session, the session should not be released.
Finally, the session will be released after all channels are disconnected.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: 7b432337 ("ksmbd: fix deadlock in ksmbd_find_crypto_ctx()")
Signed-off-by: Sasha Levin <sashal@kernel.org>