diff options
| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2018-04-10 15:21:44 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-01 15:13:08 -0700 |
| commit | 272c99cf85a371401b78f3c56a18745bf07817a3 (patch) | |
| tree | 309d59135bfc660c13521237647c32c8ac62a631 | |
| parent | a4e38e8dd596a3e03eeffb55df4aab27acd5eb2d (diff) | |
ARM: amba: Fix race condition with driver_override
commit 6a7228d90d42bcacfe38786756ba62762b91c20a 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 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>
Reviewed-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/amba/bus.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index b8642519fc92..1c25b6ee9651 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); |