tty: an overflow of multiplication in drivers/tty/cyclades.c

there is an overflow in the code : cyz_polling_cycle = (arg * HZ) / 1000, the multiplicator arg comes from user, so it may be an overflow if arg is a big number. And the value of cyc_polling_cycle will be wrong when it is used next time. Reported-by: Qixue Xiao <[email protected]> Suggested-by: Yongjian Xu <[email protected]> Suggested-by: Yu Chen <[email protected]> Signed-off-by: Qixue Xiao <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
alberto-fc · Dec 20, 2013 · 351d620 · 351d620
1 parent 4903713
commit 351d620
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/drivers/tty/cyclades.c b/drivers/tty/cyclades.c
@@ -2709,6 +2709,8 @@ cy_ioctl(struct tty_struct *tty,
 		break;
 #ifndef CONFIG_CYZ_INTR
 	case CYZSETPOLLCYCLE:
+		if (arg > LONG_MAX / HZ)
+			return -ENODEV;
 		cyz_polling_cycle = (arg * HZ) / 1000;
 		break;
 	case CYZGETPOLLCYCLE: