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    Subject[PATCH 4.15 04/55] gpio: Fix kernel stack leak to userspace
    Date
    4.15-stable review patch.  If anyone has any objections, please let me know.

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

    From: Linus Walleij <linus.walleij@linaro.org>

    commit 24bd3efc9d1efb5f756a7c6f807a36ddb6adc671 upstream.

    The GPIO event descriptor was leaking kernel stack to
    userspace because we don't zero the variable before
    use. Ooops. Fix this.

    Reported-by: Arnd Bergmann <arnd@arndb.de>
    Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>
    Reviewed-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpio/gpiolib.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/drivers/gpio/gpiolib.c
    +++ b/drivers/gpio/gpiolib.c
    @@ -732,6 +732,9 @@ static irqreturn_t lineevent_irq_thread(
    struct gpioevent_data ge;
    int ret, level;

    + /* Do not leak kernel stack to userspace */
    + memset(&ge, 0, sizeof(ge));
    +
    ge.timestamp = ktime_get_real_ns();
    level = gpiod_get_value_cansleep(le->desc);


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