PCI: Fix race condition with driver_override (9561475d) · Commits · 戴 / test

The driver_override implementation is susceptible to a race condition when different threads are reading vs. storing a different driver override. Add locking to avoid the race condition. This is in close analogy to commit ("driver core: platform: fix race condition with driver_override") from Adrian Salido. Fixes: ("PCI: Introduce new device binding path using pci_dev.driver_override") Signed-off-by:

Nicolai Stange <nstange@suse.de> Signed-off-by:

Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org # v3.16+

drivers/pci/pci-sysfs.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -686,7 +686,7 @@ static ssize_t driver_override_store(struct device *dev,
		const char *buf, size_t count)
		{
		struct pci_dev *pdev = to_pci_dev(dev);
		char driver_override, old = pdev->driver_override, *cp;
		char driver_override, old, *cp;

		/* We need to keep extra room for a newline */
		if (count >= (PAGE_SIZE - 1))
		@@ -700,12 +700,15 @@ static ssize_t driver_override_store(struct device *dev,
		if (cp)
		*cp = '\0';

		device_lock(dev);
		old = pdev->driver_override;
		if (strlen(driver_override)) {
		pdev->driver_override = driver_override;
		} else {
		kfree(driver_override);
		pdev->driver_override = NULL;
		}
		device_unlock(dev);

		kfree(old);

		@@ -716,8 +719,12 @@ static ssize_t driver_override_show(struct device *dev,
		struct device_attribute attr, char buf)
		{
		struct pci_dev *pdev = to_pci_dev(dev);
		ssize_t len;

		return snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override);
		device_lock(dev);
		len = snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override);
		device_unlock(dev);
		return len;
		}
		static DEVICE_ATTR_RW(driver_override);

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