kern/61849: Possible use of kqueue_scan on stack marker while stack swapped out

[Stephan Uphoff]

>Number:         61849
>Category:       kern
>Synopsis:       Possible use of kqueue_scan on stack marker while stack swapped out
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Jan 24 13:00:28 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Stephan Uphoff
>Release:        current
>Organization:
>Environment:
N/A  
>Description:
kqueue_scan() puts a marker element on the event list.
The marker element lives on the stack.
kqueue_scan() can block (example copyout) and its stack can
be swapped out.
The marker element might be accessed while the stack is swapped out.


>How-To-Repeat:
      
>Fix:
Use PROC_LOCK/PROC_UNLOCK to prevent swapping or use 
non stack memory for the marker element.

>Release-Note:
>Audit-Trail:
>Unformatted: