+stable

what is the status of this patch? We'd like to get it into the android common branches to fix possible double free.

On Fri, Jan 19, 2018 at 7:24 AM, Geert Uytterhoeven geert+renesas@glider.be wrote:

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 this race condition.

Cfr. commits 6265539776a0810b ("driver core: platform: fix race condition with driver_override") and 9561475db680f714 ("PCI: Fix race condition with driver_override").

Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'") Signed-off-by: Geert Uytterhoeven geert+renesas@glider.be

---

drivers/amba/bus.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 6ffd778352e6d953..36c5653ced5742b7 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -69,8 +69,12 @@ static ssize_t driver_override_show(struct device *_dev, struct device_attribute *attr, char *buf) { struct amba_device *dev = to_amba_device(_dev);

•   ssize_t len;
  
  

•   return sprintf(buf, "%s\n", dev->driver_override);
  

•   device_lock(_dev);
  

•   len = sprintf(buf, "%s\n", dev->driver_override);
  

•   device_unlock(_dev);
  

•   return len;
  

}

static ssize_t driver_override_store(struct device *_dev, @@ -78,7 +82,7 @@ static ssize_t driver_override_store(struct device *_dev, const char *buf, size_t count) { struct amba_device *dev = to_amba_device(_dev);

•   char *driver_override, *old = dev->driver_override, *cp;
  

•   char *driver_override, *old, *cp;
  
    if (count > PATH_MAX)
            return -EINVAL;
  

@@ -91,12 +95,15 @@ static ssize_t driver_override_store(struct device *_dev, if (cp) *cp = '\0';

•   device_lock(_dev);
  

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

•   device_unlock(_dev);
  
    kfree(old);
  
  

-- 2.7.4