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drivers: thermal: int340x_thermal: Fix sysfs race condition

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[ Upstream commit 129699bb8c ]

Changes since V1:
* Use dev_info instead of printk
* Use dev_warn instead of BUG_ON

Previously, sysfs_create_group was called before all initialization had
fully run - specifically, before pci_set_drvdata was called. Since the
sysctl group is visible to userspace as soon as sysfs_create_group
returns, a small window of time existed during which a process could read
from an uninitialized/partially-initialized device.

This commit moves the creation of the sysctl group to after all
initialized is completed. This ensures that it's impossible for
userspace to read from a sysctl file before initialization has fully
completed.

To catch any future regressions, I've added a check to ensure
that proc_thermal_emum_mode is never PROC_THERMAL_NONE when a process
tries to read from a sysctl file. Previously, the aforementioned race
condition could result in the 'else' branch
running while PROC_THERMAL_NONE was set,
leading to a null pointer deference.

Signed-off-by: Aaron Hill <aa1ronham@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Aaron Hill 2018-12-24 14:23:36 -05:00 committed by Greg Kroah-Hartman
parent ad5530d0c3
commit 311acb0a9f
1 changed files with 15 additions and 13 deletions
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28
drivers/thermal/int340x_thermal/processor_thermal_device.c
View file

@ -77,7 +77,12 @@ static ssize_t power_limit_##index##_##suffix##_show(struct device *dev, \
struct pci_dev *pci_dev; \
struct platform_device *pdev; \
struct proc_thermal_device *proc_dev; \
\
\
if (proc_thermal_emum_mode == PROC_THERMAL_NONE) { \
dev_warn(dev, "Attempted to get power limit before device was initialized!\n"); \
return 0; \
} \
\
if (proc_thermal_emum_mode == PROC_THERMAL_PLATFORM_DEV) { \
pdev = to_platform_device(dev); \
proc_dev = platform_get_drvdata(pdev); \
@ -291,11 +296,6 @@ static int proc_thermal_add(struct device *dev,
*priv = proc_priv;
ret = proc_thermal_read_ppcc(proc_priv);
if (!ret) {
ret = sysfs_create_group(&dev->kobj,
&power_limit_attribute_group);
}
if (ret)
return ret;
@ -309,8 +309,7 @@ static int proc_thermal_add(struct device *dev,
proc_priv->int340x_zone = int340x_thermal_zone_add(adev, ops);
if (IS_ERR(proc_priv->int340x_zone)) {
ret = PTR_ERR(proc_priv->int340x_zone);
goto remove_group;
return PTR_ERR(proc_priv->int340x_zone);
} else
ret = 0;
@ -324,9 +323,6 @@ static int proc_thermal_add(struct device *dev,
remove_zone:
int340x_thermal_zone_remove(proc_priv->int340x_zone);
remove_group:
sysfs_remove_group(&proc_priv->dev->kobj,
&power_limit_attribute_group);
return ret;
}
@ -357,7 +353,10 @@ static int int3401_add(struct platform_device *pdev)
platform_set_drvdata(pdev, proc_priv);
proc_thermal_emum_mode = PROC_THERMAL_PLATFORM_DEV;
return 0;
dev_info(&pdev->dev, "Creating sysfs group for PROC_THERMAL_PLATFORM_DEV\n");
return sysfs_create_group(&pdev->dev.kobj,
&power_limit_attribute_group);
}
static int int3401_remove(struct platform_device *pdev)
@ -434,7 +433,10 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev,
dev_err(&pdev->dev, "No auxiliary DTSs enabled\n");
}
return 0;
dev_info(&pdev->dev, "Creating sysfs group for PROC_THERMAL_PCI\n");
return sysfs_create_group(&pdev->dev.kobj,
&power_limit_attribute_group);
}
static void proc_thermal_pci_remove(struct pci_dev *pdev)