4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicolai Stange <nstange@xxxxxxx>
commit 9561475db680f7144d2223a409dd3d7e322aca03 upstream.
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 6265539776a0 ("driver core: platform:
fix race condition with driver_override") from Adrian Salido.
Fixes: 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override")
Signed-off-by: Nicolai Stange <nstange@xxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci-sysfs.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -527,7 +527,7 @@ static ssize_t driver_override_store(str
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))
@@ -541,12 +541,15 @@ static ssize_t driver_override_store(str
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);
@@ -557,8 +560,12 @@ static ssize_t driver_override_show(stru
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);