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driver core: platform: fix race condition with driver_override 

The driver_override implementation is susceptible to race condition when
different threads are reading vs storing a different driver override.
Add locking to avoid race condition.

Fixes: 3d713e0e38 ("driver core: platform: add device binding path 'driver_override'")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Salido <salidoa@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Adrian Salido 2017-04-25 16:55:26 -07:00 committed by Greg Kroah-Hartman
parent 08332893e3
commit 6265539776
1 changed files with 9 additions and 2 deletions
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11
drivers/base/platform.c
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@ -866,7 +866,7 @@ static ssize_t driver_override_store(struct device *dev,
const char *buf, size_t count)
{
struct platform_device *pdev = to_platform_device(dev);
char *driver_override, *old = pdev->driver_override, *cp;
char *driver_override, *old, *cp;
if (count > PATH_MAX)
return -EINVAL;
@ -879,12 +879,15 @@ 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);
@ -895,8 +898,12 @@ static ssize_t driver_override_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
ssize_t len;
return sprintf(buf, "%s\n", pdev->driver_override);
device_lock(dev);
len = sprintf(buf, "%s\n", pdev->driver_override);
device_unlock(dev);
return len;
}
static DEVICE_ATTR_RW(driver_override);