4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Adrian Salido <salidoa@xxxxxxxxxx>
commit 6265539776a0810b7ce6398c27866ddb9c6bd154 upstream.
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: 3d713e0e382e ("driver core: platform: add device binding path 'driver_override'")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Adrian Salido <salidoa@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/platform.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -807,7 +807,7 @@ static ssize_t driver_override_store(str
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;
@@ -820,12 +820,15 @@ 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);
@@ -836,8 +839,12 @@ static ssize_t driver_override_show(stru
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);