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, 56 insertions, 0 deletions

diff --git a/include/sound/sof/pm.h b/include/sound/sof/pm.h
new file mode 100644
index 000000000..df55bfe58
--- /dev/null
+++ b/include/sound/sof/pm.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2018 Intel Corporation
+ */
+
+#ifndef __INCLUDE_SOUND_SOF_PM_H__
+#define __INCLUDE_SOUND_SOF_PM_H__
+
+#include <sound/sof/header.h>
+
+/*
+ * PM
+ */
+
+/* PM context element */
+struct sof_ipc_pm_ctx_elem {
+	struct sof_ipc_hdr hdr;
+	uint32_t type;
+	uint32_t size;
+	uint64_t addr;
+}  __packed;
+
+/*
+ * PM context - SOF_IPC_PM_CTX_SAVE, SOF_IPC_PM_CTX_RESTORE,
+ * SOF_IPC_PM_CTX_SIZE
+ */
+struct sof_ipc_pm_ctx {
+	struct sof_ipc_cmd_hdr hdr;
+	struct sof_ipc_host_buffer buffer;
+	uint32_t num_elems;
+	uint32_t size;
+
+	/* reserved for future use */
+	uint32_t reserved[8];
+
+	struct sof_ipc_pm_ctx_elem elems[];
+} __packed;
+
+/* enable or disable cores - SOF_IPC_PM_CORE_ENABLE */
+struct sof_ipc_pm_core_config {
+	struct sof_ipc_cmd_hdr hdr;
+	uint32_t enable_mask;
+} __packed;
+
+struct sof_ipc_pm_gate {
+	struct sof_ipc_cmd_hdr hdr;
+	uint32_t flags;	/* platform specific */
+
+	/* reserved for future use */
+	uint32_t reserved[5];
+} __packed;
+
+#endif