commit fb3ce90b7d7761b6f7f28f0ff5c456ef6b5229a1
author Firo Yang <firogm@gmail.com> Fri May 26 22:37:38 2017 +0800
committer David S. Miller <davem@davemloft.net> Sat May 27 18:44:17 2017 -0400
tree 68115fc1133d475bdfa9e5cc399c20f7715d3ec5
parent 6c713a3a23154f4f0c2217ea39811ebe443dafaa

hdlcdrv: Fix divide by zero in hdlcdrv_ioctl

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>

drivers/net/hamradio/hdlcdrv.c

diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index 8c3633c..97e3bc6 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;