>Number:         34722
>Category:       lib
>Synopsis:       pthread can use unlimited amount of stack
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Oct 05 14:10:01 +0000 2006
>Originator:     YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
>Release:        NetBSD 4.99.3
>Organization:
	
>Environment:
	
	
System: NetBSD 4.99.3
Architecture: i386
Machine: i386
>Description:

(i thought i filed this PR sometime ago, but i couldn't find a number.
sorry if it was duplicated.)

1. your thread is interrupted by an upcall.
2. pthread__upcall() handles the upcall and switch back to your thread
   by pthread__upcall_switch.
3. pthread__upcall_switch switches its stack (STACK_SWITCH),
   and eventually calls _md_setcontext_u.
4. if you are unfortunate enough, _md_setcontext_u is interrupted by
   an upcall.  now, it's similar to #1, but with some more stack consumed.
5. if you are really unfortunate, you'll repeat the above sequence
   again and again, and eventually run out stack.

>How-To-Repeat:
	code inspection.
>Fix:
	

>Unformatted: