thunderbolt: Fix NULL dereference in tb_remove_work()grafted

There is a slight race between tb_remove_work() and tb_domain_remove()
which leads to dereferencing a NULL tb->root_switch pointer inside
tb_free_unplugged_xdomains():

        Thread A                            Thread B

  tb_remove_work()
                                    tb_domain_remove()
                                      mutex_lock(&tb->lock)
                                      tb_stop()
                                        /* doesn't cancel a running callback */
                                        cancel_delayed_work(&tcm->remove_work)
                                        ...
                                        tb_switch_remove(tb->root_switch)
                                        tb->root_switch = NULL
                                      mutex_unlock(&tb->lock)
    mutex_lock(&tb->lock)
    ...
    /* without checking ->root_switch */
    tb_free_unplugged_xdomains(tb->root_switch)
    mutex_unlock(&tb->lock)

Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without
holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains()
out of the &tb->lock section and the check for tb->root_switch, in
particular.  It states:

  For this reason separate removing the XDomain from the topology data
  structures (where we need the lock) from unregistering the device from
  the bus (where remove callbacks of the drivers are being called).

tb_free_unplugged_xdomains() belongs to the former group of functions
requiring the lock.  And it also calls tb_xdomain_remove() which should
only be called with &tb->lock held.

Found by Linux Verification Center (linuxtesting.org) with Svace static
analysis tool.

Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/sound/sof/dai-mediatek.h b/include/sound/sof/dai-mediatek.h
new file mode 100644
index 000000000..62dd47205
--- /dev/null
+++ b/include/sound/sof/dai-mediatek.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * Copyright(c) 2021 Mediatek Corporation. All rights reserved.
+ *
+ * Author: Bo Pan <bo.pan@mediatek.com>
+ */
+
+#ifndef __INCLUDE_SOUND_SOF_DAI_MEDIATEK_H__
+#define __INCLUDE_SOUND_SOF_DAI_MEDIATEK_H__
+
+#include <sound/sof/header.h>
+
+struct sof_ipc_dai_mtk_afe_params {
+	struct sof_ipc_hdr hdr;
+	u32 channels;
+	u32 rate;
+	u32 format;
+	u32 stream_id;
+	u32 reserved[4]; /* reserve for future */
+} __packed;
+
+#endif
+