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

PATCH New Christoph Hellwig 4 participants 4 messages May 18, 2018 – May 25, 2018

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Christoph Hellwig

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#0 lore raw

PATCH 1/1 PCI/sysfs: do not allow enabling/disabling a device with a driver

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 at lst.de>
---
 drivers/pci/pci-sysfs.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
drivers/pci/pci-sysfs.c +9 -6
index 366d93af051d..788a200fb2dc 100644
@@ -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;
 }
Signature · 1 line
2.17.0
#1 lore raw

PATCH 1/1 PCI/sysfs: do not allow enabling/disabling a device with a driver

Quoted 4 lines · 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 <[email protected]>

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

Acked-by Keith Busch <[email protected]>

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

#2 lore raw

PATCH 1/1 PCI/sysfs: do not allow enabling/disabling a device with a driver

In reply to Christoph Hellwig

Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>

Signature · 6 lines
Johannes Thumshirn                                          Storage
jthumshirn at suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Felix Imend?rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N?rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850
Applied
#3 lore raw

PATCH 1/1 PCI/sysfs: do not allow enabling/disabling a device with a driver

In reply to Christoph Hellwig
Quoted 4 lines · 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 at lst.de>

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

Quoted 34 lines
---
 drivers/pci/pci-sysfs.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
drivers/pci/pci-sysfs.c +9 -6
index 366d93af051d..788a200fb2dc 100644
@@ -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;
 }
Signature · 1 line
2.17.0