4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Firo Yang <firogm@xxxxxxxxx> [ 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@xxxxxxxxxx> Signed-off-by: Firo Yang <firogm@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/hamradio/hdlcdrv.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/net/hamradio/hdlcdrv.c +++ b/drivers/net/hamradio/hdlcdrv.c @@ -574,6 +574,8 @@ static int hdlcdrv_ioctl(struct net_devi 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;