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    Subject[PATCH 4.4 42/70] usb: misc: uss720: Fix two sleep-in-atomic-context bugs
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    4.4-stable review patch.  If anyone has any objections, please let me know.

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

    From: Jia-Ju Bai <baijiaju1990@gmail.com>

    commit bc8acc214d3f1cafebcbcd101a695bbac716595d upstream.

    async_complete() in uss720.c is a completion handler function for the
    USB driver. So it should not sleep, but it is can sleep according to the
    function call paths (from bottom to top) in Linux-4.16.

    [FUNC] set_1284_register(GFP_KERNEL)
    drivers/usb/misc/uss720.c, 372:
    set_1284_register in parport_uss720_frob_control
    drivers/parport/ieee1284.c, 560:
    [FUNC_PTR]parport_uss720_frob_control in parport_ieee1284_ack_data_avail
    drivers/parport/ieee1284.c, 577:
    parport_ieee1284_ack_data_avail in parport_ieee1284_interrupt
    ./include/linux/parport.h, 474:
    parport_ieee1284_interrupt in parport_generic_irq
    drivers/usb/misc/uss720.c, 116:
    parport_generic_irq in async_complete

    [FUNC] get_1284_register(GFP_KERNEL)
    drivers/usb/misc/uss720.c, 382:
    get_1284_register in parport_uss720_read_status
    drivers/parport/ieee1284.c, 555:
    [FUNC_PTR]parport_uss720_read_status in parport_ieee1284_ack_data_avail
    drivers/parport/ieee1284.c, 577:
    parport_ieee1284_ack_data_avail in parport_ieee1284_interrupt
    ./include/linux/parport.h, 474:
    parport_ieee1284_interrupt in parport_generic_irq
    drivers/usb/misc/uss720.c, 116:
    parport_generic_irq in async_complete

    Note that [FUNC_PTR] means a function pointer call is used.

    To fix these bugs, GFP_KERNEL is replaced with GFP_ATOMIC.

    These bugs are found by my static analysis tool DSAC.

    Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/misc/uss720.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/drivers/usb/misc/uss720.c
    +++ b/drivers/usb/misc/uss720.c
    @@ -388,7 +388,7 @@ static unsigned char parport_uss720_frob
    mask &= 0x0f;
    val &= 0x0f;
    d = (priv->reg[1] & (~mask)) ^ val;
    - if (set_1284_register(pp, 2, d, GFP_KERNEL))
    + if (set_1284_register(pp, 2, d, GFP_ATOMIC))
    return 0;
    priv->reg[1] = d;
    return d & 0xf;
    @@ -398,7 +398,7 @@ static unsigned char parport_uss720_read
    {
    unsigned char ret;

    - if (get_1284_register(pp, 1, &ret, GFP_KERNEL))
    + if (get_1284_register(pp, 1, &ret, GFP_ATOMIC))
    return 0;
    return ret & 0xf8;
    }

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