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, 144 insertions, 0 deletions

diff --git a/include/sound/sof/info.h b/include/sound/sof/info.h
new file mode 100644
index 000000000..08400fbe5
--- /dev/null
+++ b/include/sound/sof/info.h
@@ -0,0 +1,144 @@
+/* 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_INFO_H__
+#define __INCLUDE_SOUND_SOF_INFO_H__
+
+#include <sound/sof/header.h>
+#include <sound/sof/stream.h>
+
+/*
+ * Firmware boot and version
+ */
+
+#define SOF_IPC_MAX_ELEMS	16
+
+/*
+ * Firmware boot info flag bits (64-bit)
+ */
+#define SOF_IPC_INFO_BUILD		BIT(0)
+#define SOF_IPC_INFO_LOCKS		BIT(1)
+#define SOF_IPC_INFO_LOCKSV		BIT(2)
+#define SOF_IPC_INFO_GDB		BIT(3)
+#define SOF_IPC_INFO_D3_PERSISTENT	BIT(4)
+
+/* extended data types that can be appended onto end of sof_ipc_fw_ready */
+enum sof_ipc_ext_data {
+	SOF_IPC_EXT_UNUSED		= 0,
+	SOF_IPC_EXT_WINDOW		= 1,
+	SOF_IPC_EXT_CC_INFO		= 2,
+	SOF_IPC_EXT_PROBE_INFO		= 3,
+	SOF_IPC_EXT_USER_ABI_INFO	= 4,
+};
+
+/* Build u32 number in format MMmmmppp */
+#define SOF_FW_VER(MAJOR, MINOR, PATCH) ((uint32_t)( \
+	((MAJOR) << 24) | ((MINOR) << 12) | (PATCH)))
+
+/* FW version - SOF_IPC_GLB_VERSION */
+struct sof_ipc_fw_version {
+	struct sof_ipc_hdr hdr;
+	uint16_t major;
+	uint16_t minor;
+	uint16_t micro;
+	uint16_t build;
+	uint8_t date[12];
+	uint8_t time[10];
+	uint8_t tag[6];
+	uint32_t abi_version;
+	/* used to check FW and ldc file compatibility, reproducible value */
+	uint32_t src_hash;
+
+	/* reserved for future use */
+	uint32_t reserved[3];
+} __packed;
+
+/* FW ready Message - sent by firmware when boot has completed */
+struct sof_ipc_fw_ready {
+	struct sof_ipc_cmd_hdr hdr;
+	uint32_t dspbox_offset;	 /* dsp initiated IPC mailbox */
+	uint32_t hostbox_offset; /* host initiated IPC mailbox */
+	uint32_t dspbox_size;
+	uint32_t hostbox_size;
+	struct sof_ipc_fw_version version;
+
+	/* Miscellaneous flags */
+	uint64_t flags;
+
+	/* reserved for future use */
+	uint32_t reserved[4];
+} __packed;
+
+/*
+ * Extended Firmware data. All optional, depends on platform/arch.
+ */
+enum sof_ipc_region {
+	SOF_IPC_REGION_DOWNBOX	= 0,
+	SOF_IPC_REGION_UPBOX,
+	SOF_IPC_REGION_TRACE,
+	SOF_IPC_REGION_DEBUG,
+	SOF_IPC_REGION_STREAM,
+	SOF_IPC_REGION_REGS,
+	SOF_IPC_REGION_EXCEPTION,
+};
+
+struct sof_ipc_ext_data_hdr {
+	struct sof_ipc_cmd_hdr hdr;
+	uint32_t type;		/**< SOF_IPC_EXT_ */
+} __packed;
+
+struct sof_ipc_window_elem {
+	struct sof_ipc_hdr hdr;
+	uint32_t type;		/**< SOF_IPC_REGION_ */
+	uint32_t id;		/**< platform specific - used to map to host memory */
+	uint32_t flags;		/**< R, W, RW, etc - to define */
+	uint32_t size;		/**< size of region in bytes */
+	/* offset in window region as windows can be partitioned */
+	uint32_t offset;
+} __packed;
+
+/* extended data memory windows for IPC, trace and debug */
+struct sof_ipc_window {
+	struct sof_ipc_ext_data_hdr ext_hdr;
+	uint32_t num_windows;
+	struct sof_ipc_window_elem window[SOF_IPC_MAX_ELEMS];
+}  __packed;
+
+struct sof_ipc_cc_version {
+	struct sof_ipc_ext_data_hdr ext_hdr;
+	uint32_t major;
+	uint32_t minor;
+	uint32_t micro;
+
+	/* reserved for future use */
+	uint32_t reserved[4];
+
+	uint8_t name[16]; /* null terminated compiler name */
+	uint8_t optim[4]; /* null terminated compiler -O flag value */
+	uint8_t desc[32]; /* null terminated compiler description */
+} __packed;
+
+/* extended data: Probe setup */
+struct sof_ipc_probe_support {
+	struct sof_ipc_ext_data_hdr ext_hdr;
+
+	uint32_t probe_points_max;
+	uint32_t injection_dmas_max;
+
+	/* reserved for future use */
+	uint32_t reserved[2];
+} __packed;
+
+/* extended data: user abi version(s) */
+struct sof_ipc_user_abi_version {
+	struct sof_ipc_ext_data_hdr ext_hdr;
+
+	uint32_t abi_dbg_version;
+}  __packed;
+
+#endif