4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 129699bb8c7572106b5bbb2407c2daee4727ccad ]
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 --- .../processor_thermal_device.c | 28 ++++++++++--------- 1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/thermal/int340x_thermal/processor_thermal_device.c b/drivers/thermal/int340x_thermal/processor_thermal_device.c index 8e0f665cf06f8..8e1cf4d789be1 100644 --- a/drivers/thermal/int340x_thermal/processor_thermal_device.c +++ b/drivers/thermal/int340x_thermal/processor_thermal_device.c @@ -84,7 +84,12 @@ 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); \ @@ -298,11 +303,6 @@ 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;
@@ -316,8 +316,7 @@ 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;
@@ -331,9 +330,6 @@ 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; } @@ -364,7 +360,10 @@ 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) @@ -441,7 +440,10 @@ 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)