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>

5 files changed, 329 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/gnss/brcm,bcm4751.yaml b/Documentation/devicetree/bindings/gnss/brcm,bcm4751.yaml
new file mode 100644
index 000000000..c34b86bb7
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/brcm,bcm4751.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/brcm,bcm4751.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom BCM4751 family GNSS Receiver
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+  - Linus Walleij <linusw@kernel.org>
+
+description:
+  Broadcom GPS chips can be used over the UART or I2C bus. The UART
+  bus requires CTS/RTS support. The number of the capsule is more
+  elaborate than the compatibles BCM4751 may be printed
+  BCM4751IFBG for example.
+
+allOf:
+  - $ref: gnss-common.yaml#
+  - $ref: /schemas/serial/serial-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - brcm,bcm4751
+      - brcm,bcm4752
+      - brcm,bcm4753
+
+  reg:
+    description:
+      The I2C Address, not required on UART buses.
+
+  vdd-auxin-supply:
+    description:
+      Main voltage supply, pin name VDD_AUXIN, typically connected
+      directly to a battery such as LiIon 3.8V battery or a 2.6V supply.
+
+  vddio-supply:
+    description:
+      IO voltage supply, pin name VDDIO, typically 1.8V
+
+  reset-gpios:
+    maxItems: 1
+    description: An optional active low reset line, should be flagged with
+      GPIO_ACTIVE_LOW.
+
+  enable-gpios:
+    description: Enable GPIO line, connected to pins named REGPU or NSTANDBY.
+      If the line is active low such as NSTANDBY, it should be tagged
+      GPIO_ACTIVE_LOW.
+
+required:
+  - compatible
+  - enable-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    serial {
+        gnss {
+            compatible = "brcm,bcm4751";
+            vdd-auxin-supply = <&vbat>;
+            reset-gpios = <&gpio0 15 GPIO_ACTIVE_LOW>;
+            enable-gpios = <&gpio0 16 GPIO_ACTIVE_HIGH>;
+            current-speed = <38400>;
+        };
+    };
diff --git a/Documentation/devicetree/bindings/gnss/gnss-common.yaml b/Documentation/devicetree/bindings/gnss/gnss-common.yaml
new file mode 100644
index 000000000..354c05240
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/gnss-common.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/gnss-common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common Properties for Global Navigation Satellite Systems (GNSS)
+  receiver devices
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+
+description: |
+  This document defines device tree properties common to Global Navigation
+  Satellite System receivers.
+
+properties:
+  $nodename:
+    pattern: "^gnss(@.*)?$"
+
+  lna-supply:
+    description: A separate regulator supplying power for the Low Noise
+      Amplifier (LNA). This is an amplifier connected between the GNSS
+      device and the receiver antenna.
+
+  enable-gpios:
+    description: A GPIO line that will enable the GNSS receiver when
+      asserted. If this line is active low, the GPIO phandle should
+      consequently be tagged with the GPIO_ACTIVE_LOW flag so the operating
+      system can rely on asserting the line to enable the GNSS device.
+    maxItems: 1
+
+  timepulse-gpios:
+    description: Timepulse signal
+    maxItems: 1
+
+additionalProperties: true
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    serial {
+      gnss {
+        compatible = "u-blox,neo-8";
+        vcc-supply = <&gnss_reg>;
+        timepulse-gpios = <&gpio0 16 GPIO_ACTIVE_HIGH>;
+        current-speed = <4800>;
+      };
+    };
diff --git a/Documentation/devicetree/bindings/gnss/mediatek.yaml b/Documentation/devicetree/bindings/gnss/mediatek.yaml
new file mode 100644
index 000000000..2b9e5be4e
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/mediatek.yaml
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/mediatek.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Mediatek GNSS Receiver
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+
+description:
+  Mediatek chipsets are used in GNSS-receiver modules produced by several
+  vendors and can use a UART interface.
+
+allOf:
+  - $ref: gnss-common.yaml#
+  - $ref: /schemas/serial/serial-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: globaltop,pa6h
+
+  vcc-supply:
+    description:
+      Main voltage regulator, pin name VCC.
+
+  reset-gpios:
+    maxItems: 1
+    description: An optional reset line, with names such as RESET or NRESET.
+      If the line is active low it should be flagged with GPIO_ACTIVE_LOW.
+
+  timepulse-gpios:
+    description: Comes with pin names such as PPS1 or 1PPS.
+
+  gnss-fix-gpios:
+    maxItems: 1
+    description: GPIO used to determine device position fix state, pin names
+      FIX or 3D_FIX.
+
+  vbackup-supply:
+    description:
+      Regulator providing backup voltage, pin names such as VBAT or VBACKUP.
+
+required:
+  - compatible
+  - vcc-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    serial {
+        gnss {
+            compatible = "globaltop,pa6h";
+            vcc-supply = <&vcc_3v3>;
+            reset-gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
+        };
+    };
diff --git a/Documentation/devicetree/bindings/gnss/sirfstar.yaml b/Documentation/devicetree/bindings/gnss/sirfstar.yaml
new file mode 100644
index 000000000..7e5da89a5
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/sirfstar.yaml
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/sirfstar.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SiRFstar GNSS Receiver
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+
+description:
+  The SiRFstar GNSS receivers have incarnated over the years in different
+  chips, starting from the SiRFstarIII which was a chip that was introduced in
+  2004 and used in a lot of dedicated GPS devices. In 2009 SiRF was acquired
+  by CSR (Cambridge Silicon Radio) and in 2012 the CSR GPS business was
+  acquired by Samsung, while some products remained with CSR. In 2014 CSR
+  was acquired by Qualcomm who still sell some of the SiRF products.
+
+  SiRF chips can be used over UART, I2C or SPI buses.
+
+allOf:
+  - $ref: gnss-common.yaml#
+  - $ref: /schemas/serial/serial-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - csr,gsd4t
+      - csr,csrg05ta03-icje-r
+      - fastrax,uc430
+      - linx,r4
+      - wi2wi,w2sg0004
+      - wi2wi,w2sg0008i
+      - wi2wi,w2sg0084i
+
+  reg:
+    description:
+      The I2C Address, SPI chip select address. Not required on UART buses.
+
+  vcc-supply:
+    description:
+      Main voltage regulator, pin names such as 3V3_IN, VCC, VDD.
+
+  reset-gpios:
+    maxItems: 1
+    description: An optional active low reset line, should be flagged with
+      GPIO_ACTIVE_LOW.
+
+  sirf,onoff-gpios:
+    maxItems: 1
+    description: GPIO used to power on and off device, pin name ON_OFF.
+
+  sirf,wakeup-gpios:
+    maxItems: 1
+    description: GPIO used to determine device power state, pin names such
+      as RFPWRUP, WAKEUP.
+
+required:
+  - compatible
+  - vcc-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    serial {
+        gnss {
+            compatible = "wi2wi,w2sg0084i";
+            vcc-supply = <&gnss_vcc_reg>;
+            reset-gpios = <&gpio0 15 GPIO_ACTIVE_LOW>;
+            sirf,onoff-gpios = <&gpio0 16 GPIO_ACTIVE_HIGH>;
+            sirf,wakeup-gpios = <&gpio0 17 GPIO_ACTIVE_HIGH>;
+            current-speed = <38400>;
+        };
+    };
diff --git a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
new file mode 100644
index 000000000..b349b7bc0
--- /dev/null
+++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/u-blox,neo-6m.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: u-blox GNSS receiver
+
+allOf:
+  - $ref: gnss-common.yaml#
+  - $ref: /schemas/serial/serial-peripheral-props.yaml#
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+
+description: >
+  The u-blox GNSS receivers can use UART, DDC (I2C), SPI and USB interfaces.
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - u-blox,neo-6m
+          - u-blox,neo-8
+          - u-blox,neo-m8
+      - items:
+          - const: u-blox,neo-m9
+          - const: u-blox,neo-m8
+
+  reg:
+    description: >
+      The DDC Slave Address, SPI chip select address, the number of the USB hub
+      port or the USB host-controller port to which this device is attached,
+      depending on the bus used. Required for the DDC, SPI or USB busses.
+
+  reset-gpios:
+    maxItems: 1
+
+  safeboot-gpios:
+    maxItems: 1
+
+  vcc-supply:
+    description: >
+      Main voltage regulator
+
+  u-blox,extint-gpios:
+    maxItems: 1
+    description: >
+      GPIO connected to the "external interrupt" input pin
+
+  v-bckp-supply:
+    description: >
+      Backup voltage regulator
+
+required:
+  - compatible
+  - vcc-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    serial {
+        gnss {
+            compatible = "u-blox,neo-8";
+            v-bckp-supply = <&gnss_v_bckp_reg>;
+            vcc-supply = <&gnss_vcc_reg>;
+            reset-gpios = <&gpio 1 (GPIO_ACTIVE_LOW | GPIO_OPEN_DRAIN)>;
+            safeboot-gpios = <&gpio 2 (GPIO_ACTIVE_LOW | GPIO_OPEN_DRAIN)>;
+        };
+    };