UPSTREAM: driver core: platform: fix race condition with driver_override
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@vger.kernel.org
Signed-off-by: Adrian Salido <salidoa@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
BUG=b:65880174
TEST=trybots
(cherry picked from commit c01ace719ebe6353f0c96e56f6c75c22ad3f67b0)
Signed-off-by: Aditya Kali <adityakali@google.com>
Change-Id: I20e76f432dfa8d6a178c2cf42721a5a0dfce3255
Reviewed-on: https://chromium-review.googlesource.com/677057
Reviewed-by: Daniel Wang <wonderfly@google.com>
Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
Tested-by: Aditya Kali <adityakali@google.com>
Commit-Queue: Aditya Kali <adityakali@google.com>
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 3e56e3d..da3b230 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -806,7 +806,7 @@
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;
@@ -819,12 +819,15 @@
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);
@@ -835,8 +838,12 @@
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);
