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kern/36658: systrace locks the system

Subject: kern/36658: systrace locks the system
From:
Date: Mon, 16 Jul 2007 14:01:32 UTC
Newsgroups: fa.netbsd.bugs

>Number:         36658
>Category:       kern
>Synopsis:       systrace locks the system
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 16 14:00:00 +0000 2007
>Originator:     Julio M. Merino Vidal
>Release:        NetBSD 4.99.23
>Organization:
        
>Environment:
        
        
System: NetBSD vm-nb-head 4.99.23 NetBSD 4.99.23 (GENERIC_DIAGNOSTIC) #2: Sun 
Jul 15 16:02:35 CEST 2007 
jmmv@xxxxxxxxxxxxxxxxxxxx:/Volumes/NetBSD/obj.i386/Volumes/NetBSD/src/sys/arch/i386/compile/GENERIC_DIAGNOSTIC
 i386
Architecture: i386
Machine: i386
>Description:
        When running the systrace tool against a binary in the system
        (after enabling 'options SYSTRACE' in the kernel), the machine
        locks up.  I cannot cancel the systrace command nor do anything
        else, except type characters which are not recognized by the
        system.  For example, characters will keep appearing on the
        console where I ran systrace, but if I switch to a different
        virtual terminal and try to log in, the key presses are not
        recognized.

        If I later enter ddb and ask for a 'sync', the kernel spits out
        a diagnostic assertion about locking.  Maybe, just maybe, this
        problem has been introducing with ad@'s work.  But I really don't
        know.

        I'm not marking this as critical nor serious because systrace is
        not enabled by default and supposedly it doesn't work correctly
        (or at least that's what I recall hearing).
>How-To-Repeat:
        Trivial.  Build a kernel with 'options SYSTRACE' support and
        preferably 'options DIAGNOSTIC' too and run 'systrace /bin/ls'.
        I doubt that command is correct anyway, but it is enough to expose
        the problem.

        Example:

        vm-nb-head:~> systrace /bin/ls
        Error: Can't open display:
        systrace: EOF on policy input request: No such file or directory
        ... here I hit ctrl+alt+esc ...
        Stopped in pid 456.1 (systrace) at netbsd:cpu_Debugger+0x4: popl %ebp
        db> sync
        syncing disks... panic: kernel diagnostic assertion "lwp_locked(l, 
&l->l_cpu->ci_schedstate.spc_lwplock)" failed: file 
"/Volumes/NetBSD/src/sys/kern/kern_synch.c", line 305
        Stopped in pid 456.1 (systrace) at netbsd:cpu_Debugger+0x4: popl %ebp
        db>
>Fix:
        Don't know.

>Unformatted:
        
        

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