regulator: core: Use different devices for resource allocation and DT lookup

Following by the below discussion, there's the potential UAF issue
between regulator and mfd.
https://lore.kernel.org/all/20221128143601.1698148-1-yangyingliang@huawei.com/

From the analysis of Yingliang

CPU A				|CPU B
mt6370_probe()			|
  devm_mfd_add_devices()	|
				|mt6370_regulator_probe()
				|  regulator_register()
				|    //allocate init_data and add it to devres
				|    regulator_of_get_init_data()
i2c_unregister_device()		|
  device_del()			|
    devres_release_all()	|
      // init_data is freed	|
      release_nodes()		|
				|  // using init_data causes UAF
				|  regulator_register()

It's common to use mfd core to create child device for the regulator.
In order to do the DT lookup for init data, the child that registered
the regulator would pass its parent as the parameter. And this causes
init data resource allocated to its parent, not itself. The issue happen
when parent device is going to release and regulator core is still doing
some operation of init data constraint for the regulator of child device.

To fix it, this patch expand 'regulator_register' API to use the
different devices for init data allocation and DT lookup.

Reported-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1670311341-32664-1-git-send-email-u0084500@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/platform/x86/intel/int3472/clk_and_regulator.c b/drivers/platform/x86/intel/int3472/clk_and_regulator.c
index 1cf958983e8680565d407c4b094b9c1d2505a833..b2342b3d78c7234303bb6155005f00b82c797cea 100644 (file)
--- a/drivers/platform/x86/intel/int3472/clk_and_regulator.c
+++ b/drivers/platform/x86/intel/int3472/clk_and_regulator.c
@@ -185,7 +185,8 @@ int skl_int3472_register_regulator(struct int3472_discrete_device *int3472,
        cfg.init_data = &init_data;
        cfg.ena_gpiod = int3472->regulator.gpio;
 
-       int3472->regulator.rdev = regulator_register(&int3472->regulator.rdesc,
+       int3472->regulator.rdev = regulator_register(int3472->dev,
+                                                    &int3472->regulator.rdesc,
                                                     &cfg);
        if (IS_ERR(int3472->regulator.rdev)) {
                ret = PTR_ERR(int3472->regulator.rdev);

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 8258facc697b8f665e8d44deaf444f938da09bce..c84e8d78dc7ed2bd0bce68bea22fcfcfa43114e7 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5409,6 +5409,7 @@ static struct regulator_coupler generic_regulator_coupler = {
 
 /**
  * regulator_register - register regulator
+ * @dev: the device that drive the regulator
  * @regulator_desc: regulator to register
  * @cfg: runtime configuration for regulator
  *
@@ -5417,7 +5418,8 @@ static struct regulator_coupler generic_regulator_coupler = {
  * or an ERR_PTR() on error.
  */
 struct regulator_dev *
-regulator_register(const struct regulator_desc *regulator_desc,
+regulator_register(struct device *dev,
+                  const struct regulator_desc *regulator_desc,
                   const struct regulator_config *cfg)
 {
        const struct regulator_init_data *init_data;
@@ -5426,7 +5428,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
        struct regulator_dev *rdev;
        bool dangling_cfg_gpiod = false;
        bool dangling_of_gpiod = false;
-       struct device *dev;
        int ret, i;
        bool resolved_early = false;
 
@@ -5439,8 +5440,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
                goto rinse;
        }
 
-       dev = cfg->dev;
-       WARN_ON(!dev);
+       WARN_ON(!dev || !cfg->dev);
 
        if (regulator_desc->name == NULL || regulator_desc->ops == NULL) {
                ret = -EINVAL;

diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
index fec0398d98b083054d1f222665bdcdad80eead5f..90bb0d178885afa881678a6ed32b08752e7b5cdc 100644 (file)
--- a/drivers/regulator/devres.c
+++ b/drivers/regulator/devres.c
@@ -415,7 +415,7 @@ struct regulator_dev *devm_regulator_register(struct device *dev,
        if (!ptr)
                return ERR_PTR(-ENOMEM);
 
-       rdev = regulator_register(regulator_desc, config);
+       rdev = regulator_register(dev, regulator_desc, config);
        if (!IS_ERR(rdev)) {
                *ptr = rdev;
                devres_add(dev, ptr);

diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
index f7529f1bf8b2e996153ed9601144d60524f12deb..1b65e5e4e40ffc281b69b632299cfaa6b034473a 100644 (file)
--- a/drivers/regulator/of_regulator.c
+++ b/drivers/regulator/of_regulator.c
@@ -505,7 +505,7 @@ struct regulator_init_data *regulator_of_get_init_data(struct device *dev,
        struct device_node *child;
        struct regulator_init_data *init_data = NULL;
 
-       child = regulator_of_get_init_node(dev, desc);
+       child = regulator_of_get_init_node(config->dev, desc);
        if (!child)
                return NULL;
 

diff --git a/drivers/regulator/stm32-vrefbuf.c b/drivers/regulator/stm32-vrefbuf.c
index 30ea3bc8ca1921ced12c21c8c418475e6864db1b..7a454b7b6eab9958ad28ef2ba09739f3b893ce2c 100644 (file)
--- a/drivers/regulator/stm32-vrefbuf.c
+++ b/drivers/regulator/stm32-vrefbuf.c
@@ -210,7 +210,7 @@ static int stm32_vrefbuf_probe(struct platform_device *pdev)
                                                      pdev->dev.of_node,
                                                      &stm32_vrefbuf_regu);
 
-       rdev = regulator_register(&stm32_vrefbuf_regu, &config);
+       rdev = regulator_register(&pdev->dev, &stm32_vrefbuf_regu, &config);
        if (IS_ERR(rdev)) {
                ret = PTR_ERR(rdev);
                dev_err(&pdev->dev, "register failed with error %d\n", ret);

diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index f9a7461e72b80ef345ef3165262ac82bce201ed7..d3b4a3d4514aba340650c673b8a34c05132cb348 100644 (file)
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -687,7 +687,8 @@ static inline int regulator_err2notif(int err)
 
 
 struct regulator_dev *
-regulator_register(const struct regulator_desc *regulator_desc,
+regulator_register(struct device *dev,
+                  const struct regulator_desc *regulator_desc,
                   const struct regulator_config *config);
 struct regulator_dev *
 devm_regulator_register(struct device *dev,