kern/94238: 32 bit overflow prevents proper setting of base in tc_cpu_ticks()

[Tim Kuik]

>Number:         94238
>Category:       kern
>Synopsis:       32 bit overflow prevents proper setting of base in tc_cpu_ticks()
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Mar 08 19:50:09 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Tim Kuik
>Release:        current
>Organization:
Cisco
>Environment:
FreeBSD tkuik-freebsd.cisco 7.0-CURRENT FreeBSD 7.0-CURRENT #0: Mon Mar  6 12:49:57 CST 2006     root at tkuik-freebsd.cisco:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
in kern_tc.c: tc_cpu_ticks(), the line
base += tc->tc_counter_mask + 1;
will cause a 32 bit overflow if the tc_counter_mask is 0xffffffff, resulting in base not being incremented.
>How-To-Repeat:
As long as the mask is set to 0xffffffff, it will always happen.
>Fix:
Change the line to:
base += (uint64_t)(tc->tc_counter_mask) + 1;
>Release-Note:
>Audit-Trail:
>Unformatted: