[PATCH] PCI/sysfs: do not allow enabling/disabling a device with a driver

[PATCH] PCI/sysfs: do not allow enabling/disabling a device with a driver

[Christoph Hellwig]

Manpulating the enable_cnt behind the back of the driver will wreck
complete havok with the kernel state, so disallow it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/pci/pci-sysfs.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 366d93af051d..788a200fb2dc 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -288,13 +288,16 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!val) {
-		if (pci_is_enabled(pdev))
-			pci_disable_device(pdev);
-		else
-			result = -EIO;
-	} else
+	device_lock(dev);
+	if (dev->driver)
+		result = -EBUSY;
+	else if (val)
 		result = pci_enable_device(pdev);
+	else if (pci_is_enabled(pdev))
+		pci_disable_device(pdev);
+	else
+		result = -EIO;
+	device_unlock(dev);
 
 	return result < 0 ? result : count;
 }
-- 
2.17.0

Re: [PATCH] PCI/sysfs: do not allow enabling/disabling a device with a driver

[Keith Busch]

On Fri, May 18, 2018 at 06:56:24PM +0200, Christoph Hellwig wrote:
> Manpulating the enable_cnt behind the back of the driver will wreck
> complete havok with the kernel state, so disallow it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Nice, looks like you beat me to it, and used device locking that I
missed.

Acked-by: Keith Busch <keith.busch@intel.com>

Bjorn,
Please disregard https://marc.info/?l=linux-pci&m=152666267830742&w=2

Re: [PATCH] PCI/sysfs: do not allow enabling/disabling a device with a driver

[Johannes Thumshirn]

Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
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jthumshirn@suse.de                                +49 911 74053 689
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Re: [PATCH] PCI/sysfs: do not allow enabling/disabling a device with a driver

[Bjorn Helgaas]

On Fri, May 18, 2018 at 06:56:24PM +0200, Christoph Hellwig wrote:
> Manpulating the enable_cnt behind the back of the driver will wreck
> complete havok with the kernel state, so disallow it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Applied to pci/enumeration for v4.18, thanks!

> ---
>  drivers/pci/pci-sysfs.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 366d93af051d..788a200fb2dc 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -288,13 +288,16 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>  
> -	if (!val) {
> -		if (pci_is_enabled(pdev))
> -			pci_disable_device(pdev);
> -		else
> -			result = -EIO;
> -	} else
> +	device_lock(dev);
> +	if (dev->driver)
> +		result = -EBUSY;
> +	else if (val)
>  		result = pci_enable_device(pdev);
> +	else if (pci_is_enabled(pdev))
> +		pci_disable_device(pdev);
> +	else
> +		result = -EIO;
> +	device_unlock(dev);
>  
>  	return result < 0 ? result : count;
>  }
> -- 
> 2.17.0
> 

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