linux-kernel - [PATCH] driver core: platform: fix race condition with driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170425235526.GA165155@google.com>
Date:   Tue, 25 Apr 2017 16:55:26 -0700
From:   Adrian Salido <salidoa@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org
Subject: [PATCH] driver core: platform: fix race condition with
 driver_override

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@...r.kernel.org
Signed-off-by: Adrian Salido <salidoa@...gle.com>
---
 drivers/base/platform.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index c2456839214a..493e03fa0e07 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -866,7 +866,7 @@ static ssize_t driver_override_store(struct device *dev,
 				     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;
@@ -879,12 +879,15 @@ static ssize_t driver_override_store(struct device *dev,
 	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);
 
@@ -895,8 +898,12 @@ static ssize_t driver_override_show(struct device *dev,
 				    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);
 
-- 
2.13.0.rc0.306.g87b477812d-goog