[PATCH] ax25: unsigned cannot be less than 0 in ax25_ctl_ioctl()

[Roel Kluin <roel.kluin@gmail.com>]

struct ax25_ctl_struct member `arg' is unsigned and cannot be less
than 0.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
If the ax25_ctl.arg limit is known to be lower, please suggest
other values.

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index f454607..0d99704 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -398,14 +398,14 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
 		break;
 
 	case AX25_T1:
-		if (ax25_ctl.arg < 1)
+		if (ax25_ctl.arg < 1 || ax25_ctl.arg * HZ > ULONG_MAX)
 			goto einval_put;
 		ax25->rtt = (ax25_ctl.arg * HZ) / 2;
 		ax25->t1  = ax25_ctl.arg * HZ;
 		break;
 
 	case AX25_T2:
-		if (ax25_ctl.arg < 1)
+		if (ax25_ctl.arg < 1 || ax25_ctl.arg * HZ > ULONG_MAX)
 			goto einval_put;
 		ax25->t2 = ax25_ctl.arg * HZ;
 		break;
@@ -418,13 +418,13 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
 		break;
 
 	case AX25_T3:
-		if (ax25_ctl.arg < 0)
+		if (ax25_ctl.arg * HZ > ULONG_MAX)
 			goto einval_put;
 		ax25->t3 = ax25_ctl.arg * HZ;
 		break;
 
 	case AX25_IDLE:
-		if (ax25_ctl.arg < 0)
+		if (ax25_ctl.arg * 60 * HZ > ULONG_MAX)
 			goto einval_put;
 		ax25->idle = ax25_ctl.arg * 60 * HZ;
 		break;