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    Subject[PATCH 4.12 01/27] driver core: platform: fix race condition with driver_override
    Date
    4.12-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Adrian Salido <salidoa@google.com>

    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>

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

    --- a/drivers/base/platform.c
    +++ b/drivers/base/platform.c
    @@ -866,7 +866,7 @@ static ssize_t driver_override_store(str
    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(str
    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(stru
    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);


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