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    Subject[PATCH AUTOSEL for 4.9 152/281] hdlcdrv: Fix divide by zero in hdlcdrv_ioctl
    Date
    From: Firo Yang <firogm@gmail.com>

    [ Upstream commit fb3ce90b7d7761b6f7f28f0ff5c456ef6b5229a1 ]

    syszkaller fuzzer triggered a divide by zero, when set calibration
    through ioctl().

    To fix it, test 'bitrate' if it is negative or 0, just return -EINVAL.

    Reported-by: Andrey Konovalov <andreyknvl@google.com>
    Signed-off-by: Firo Yang <firogm@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    drivers/net/hamradio/hdlcdrv.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
    index 4bad0b894e9c..27160d1870e1 100644
    --- a/drivers/net/hamradio/hdlcdrv.c
    +++ b/drivers/net/hamradio/hdlcdrv.c
    @@ -576,6 +576,8 @@ static int hdlcdrv_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
    case HDLCDRVCTL_CALIBRATE:
    if(!capable(CAP_SYS_RAWIO))
    return -EPERM;
    + if (s->par.bitrate <= 0)
    + return -EINVAL;
    if (bi.data.calibrate > INT_MAX / s->par.bitrate)
    return -EINVAL;
    s->hdlctx.calibrate = bi.data.calibrate * s->par.bitrate / 16;
    --
    2.14.1
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