From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Russell King <linux@armlinux.org.uk>
Cc: Antonios Motakis <a.motakis@virtualopensystems.com>,
Adrian Salido <salidoa@google.com>,
Sasha Levin <sasha.levin@oracle.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 2/4] ARM: amba: Fix race condition with driver_override
Date: Fri, 19 Jan 2018 16:24:08 +0100 [thread overview]
Message-ID: <1516375450-30575-3-git-send-email-geert+renesas@glider.be> (raw)
In-Reply-To: <1516375450-30575-1-git-send-email-geert+renesas@glider.be>
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
next prev parent reply other threads:[~2018-01-19 15:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-19 15:24 [PATCH 0/4] ARM: amba: driver_override improvements Geert Uytterhoeven
2018-01-19 15:24 ` [PATCH 1/4] ARM: amba: Make driver_override output consistent with other buses Geert Uytterhoeven
2018-01-19 15:24 ` Geert Uytterhoeven [this message]
2018-03-02 18:23 ` [PATCH 2/4] ARM: amba: Fix race condition with driver_override Todd Kjos
2018-03-05 8:08 ` Geert Uytterhoeven
2018-01-19 15:24 ` [PATCH 3/4] ARM: amba: Don't read past the end of sysfs "driver_override" buffer Geert Uytterhoeven
2018-01-19 15:24 ` [PATCH 4/4] ARM: amba: Fix wrong indentation in driver_override_store() Geert Uytterhoeven
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