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>

7 files changed, 432 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-ibt-bmc.yaml b/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-ibt-bmc.yaml
new file mode 100644
index 000000000..c4f7cdbbe
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-ibt-bmc.yaml
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/aspeed,ast2400-ibt-bmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Aspeed Block Transfer (BT) IPMI interface
+
+maintainers:
+  - Joel Stanley <joel@jms.id.au>
+
+properties:
+  compatible:
+    enum:
+      - aspeed,ast2400-ibt-bmc
+      - aspeed,ast2500-ibt-bmc
+      - aspeed,ast2600-ibt-bmc
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/aspeed-clock.h>
+
+    bt@1e789140 {
+        compatible = "aspeed,ast2400-ibt-bmc";
+        reg = <0x1e789140 0x18>;
+        interrupts = <8>;
+        clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-kcs-bmc.yaml b/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-kcs-bmc.yaml
new file mode 100644
index 000000000..610c79863
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/aspeed,ast2400-kcs-bmc.yaml
@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/aspeed,ast2400-kcs-bmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED BMC KCS Devices
+
+maintainers:
+  - Andrew Jeffery <andrew@aj.id.au>
+
+description: |
+  The Aspeed BMC SoCs typically use the Keyboard-Controller-Style (KCS)
+  interfaces on the LPC bus for in-band IPMI communication with their host.
+
+properties:
+  compatible:
+    oneOf:
+      - description: Channel ID derived from reg
+        items:
+          enum:
+            - aspeed,ast2400-kcs-bmc-v2
+            - aspeed,ast2500-kcs-bmc-v2
+            - aspeed,ast2600-kcs-bmc
+
+      - description: Old-style with explicit channel ID, no reg
+        deprecated: true
+        items:
+          enum:
+            - aspeed,ast2400-kcs-bmc
+            - aspeed,ast2500-kcs-bmc
+
+  interrupts:
+    maxItems: 1
+
+  reg:
+    # maxItems: 3
+    items:
+      - description: IDR register
+      - description: ODR register
+      - description: STR register
+
+  clocks:
+    maxItems: 1
+
+  aspeed,lpc-io-reg:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 1
+    maxItems: 2
+    description: |
+      The host CPU LPC IO data and status addresses for the device. For most
+      channels the status address is derived from the data address, but the
+      status address may be optionally provided.
+
+  aspeed,lpc-interrupts:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 2
+    maxItems: 2
+    description: |
+      A 2-cell property expressing the LPC SerIRQ number and the interrupt
+      level/sense encoding (specified in the standard fashion).
+
+      Note that the generated interrupt is issued from the BMC to the host, and
+      thus the target interrupt controller is not captured by the BMC's
+      devicetree.
+
+  kcs_chan:
+    deprecated: true
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: The LPC channel number in the controller
+
+  kcs_addr:
+    deprecated: true
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: The host CPU IO map address
+
+required:
+  - compatible
+  - interrupts
+
+additionalProperties: false
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - aspeed,ast2400-kcs-bmc
+              - aspeed,ast2500-kcs-bmc
+    then:
+      required:
+        - kcs_chan
+        - kcs_addr
+    else:
+      required:
+        - reg
+        - aspeed,lpc-io-reg
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    kcs3: kcs@24 {
+        compatible = "aspeed,ast2600-kcs-bmc";
+        reg = <0x24 0x1>, <0x30 0x1>, <0x3c 0x1>;
+        aspeed,lpc-io-reg = <0xca2>;
+        aspeed,lpc-interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
+        interrupts = <8>;
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml b/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml
new file mode 100644
index 000000000..8b0d71901
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/ipmb-dev.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: The Intelligent Platform Management Bus(IPMB) Device
+
+description: |
+  The IPMB is an I2C bus which provides interconnection between a Baseboard
+  Management Controller(BMC) and chassis electronics. The BMC sends IPMI
+  requests to intelligent controllers like Satellite Management Controller(MC)
+  devices via IPMB and the device sends responses back to the BMC.
+  This device uses an I2C slave device to send and receive IPMB messages,
+  either on a BMC or other MC. A miscellaneous device provices a user space
+  program to communicate with the kernel and the backend device. Some IPMB
+  devices only support the I2C protocol and not the SMB protocol.
+
+  IPMB communications protocol Specification V1.0
+  https://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/ipmp-spec-v1.0.pdf
+
+maintainers:
+  - Ninad Palsule <ninad@linux.ibm.com>
+
+properties:
+  compatible:
+    enum:
+      - ipmb-dev
+
+  reg:
+    maxItems: 1
+
+  i2c-protocol:
+    description:
+      Use I2C block transfer instead of SMBUS block transfer.
+    type: boolean
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/i2c/i2c.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ipmb-dev@10 {
+            compatible = "ipmb-dev";
+            reg = <(0x10 | I2C_OWN_SLAVE_ADDRESS)>;
+            i2c-protocol;
+        };
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/ipmi-ipmb.yaml b/Documentation/devicetree/bindings/ipmi/ipmi-ipmb.yaml
new file mode 100644
index 000000000..52647bff3
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/ipmi-ipmb.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/ipmi-ipmb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IPMI IPMB device
+
+description: IPMI IPMB device bindings
+
+maintainers:
+  - Corey Minyard <cminyard@mvista.com>
+
+properties:
+  compatible:
+    enum:
+      - ipmi-ipmb
+
+  device_type:
+    items:
+      - const: ipmi
+
+  reg:
+    maxItems: 1
+
+  bmcaddr:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    description: The address of the BMC on the IPMB bus.  Defaults to 0x20.
+
+  retry-time:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      Time between retries of sends, in milliseconds.  Defaults to 250.
+
+  max-retries:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Number of retries before a failure is declared.  Defaults to 1.
+
+  slave-dev:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: |
+      The slave i2c device.  If not present, the main device is used. This
+      lets you use two devices on the IPMB, one for master and one for slave,
+      in case you have a slave device that can only be a slave.  The slave
+      will receive messages and the master will transmit.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            ipmi-ipmb@40 {
+                    compatible = "ipmi-ipmb";
+                    device_type = "ipmi";
+                    reg = <0x40>;
+                    bmcaddr = /bits/ 8 <0x20>;
+                    retry-time = <250>;
+                    max-retries = <1>;
+            };
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/ipmi-smic.yaml b/Documentation/devicetree/bindings/ipmi/ipmi-smic.yaml
new file mode 100644
index 000000000..4bffa3d86
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/ipmi-smic.yaml
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/ipmi-smic.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IPMI device
+
+description: IPMI device bindings
+
+maintainers:
+  - Corey Minyard <cminyard@mvista.com>
+
+properties:
+  compatible:
+    enum:
+      - ipmi-kcs
+      - ipmi-smic
+      - ipmi-bt
+
+  device_type:
+    items:
+      - const: ipmi
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description: Interface is polled if this property is omitted.
+    maxItems: 1
+
+  reg-size:
+    description: The access width of the register in bytes. Defaults to 1.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2, 4, 8]
+
+  reg-spacing:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: The number of bytes between register starts. Defaults to 1.
+
+  reg-shift:
+    description: |
+      The amount of bits to shift the register content to the right to get
+      the data into bit zero.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 56
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    smic@fff3a000 {
+        compatible = "ipmi-smic";
+        device_type = "ipmi";
+        reg = <0xfff3a000 0x1000>;
+        interrupts = <0 24 4>;
+        reg-size = <4>;
+        reg-spacing = <4>;
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/nuvoton,npcm750-kcs-bmc.yaml b/Documentation/devicetree/bindings/ipmi/nuvoton,npcm750-kcs-bmc.yaml
new file mode 100644
index 000000000..fc5df1c5e
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/nuvoton,npcm750-kcs-bmc.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/nuvoton,npcm750-kcs-bmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton NPCM KCS BMC
+
+maintainers:
+  - Avi Fishman <avifishman70@gmail.com>
+  - Tomer Maimon <tmaimon77@gmail.com>
+  - Tali Perry <tali.perry1@gmail.com>
+
+description:
+  The Nuvoton SOCs (NPCM) are commonly used as BMCs (Baseboard Management
+  Controllers) and the KCS interface can be used to perform in-band IPMI
+  communication with their host.
+
+properties:
+  compatible:
+    oneOf:
+      - const: nuvoton,npcm750-kcs-bmc
+      - items:
+          - enum:
+              - nuvoton,npcm845-kcs-bmc
+          - const: nuvoton,npcm750-kcs-bmc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  kcs_chan:
+    description: The KCS channel number in the controller
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 3
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - kcs_chan
+
+additionalProperties: false
+
+examples:
+  - |
+    kcs@0 {
+        compatible = "nuvoton,npcm750-kcs-bmc";
+        reg = <0x0 0x40>;
+        interrupts = <9 4>;
+        kcs_chan = <1>;
+    };
diff --git a/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml b/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml
new file mode 100644
index 000000000..02b662d78
--- /dev/null
+++ b/Documentation/devicetree/bindings/ipmi/ssif-bmc.yaml
@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/ssif-bmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SSIF IPMI BMC interface
+
+description: SSIF IPMI BMC device bindings
+
+maintainers:
+  - Quan Nguyen <quan@os.amperecomputing.com>
+
+properties:
+  compatible:
+    enum:
+      - ssif-bmc
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ssif-bmc@10 {
+            compatible = "ssif-bmc";
+            reg = <0x10>;
+        };
+    };