patch 9.0.2111: [security]: overflow in get_number

Problem:  [security]: overflow in get_number
Solution: Return 0 when the count gets too large

[security]: overflow in get_number

When using the z= command, we may overflow the count with values larger
than MAX_INT. So verify that we do not overflow and in case when an
overflow is detected, simply return 0

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/misc1.c

@@ -975,6 +975,8 @@ get_number(
 	c = safe_vgetc();
 	if (VIM_ISDIGIT(c))
 	{
+	    if (n > INT_MAX / 10)
+		return 0;
 	    n = n * 10 + c - '0';
 	    msg_putchar(c);
 	    ++typed;