bin/58692: opensnoop fails -- dtrace fails printing arg0

[nmingotti%gmail.com@localhost]

>Number:         58692
>Category:       bin
>Synopsis:       opensnoop fails -- dtrace fails printing arg0
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Sep 24 15:40:00 +0000 2024
>Originator:     Dr. Nicola Mingotti
>Release:        10.0
>Organization:
Borghi SRL
>Environment:
NetBSD netb1.borghi.lan 10.0 NetBSD 10.0 (GENERIC) #0: Thu Mar 28 08:33:33 UTC 2024  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:

. /usr/sbin/opensnoop fails giving (as soon as a file is open) a lot of errors

. The problem appears to be related to dtrace printing arg0

>How-To-Repeat:

$> doas /usr/sbin/opensnoop
---------- output --------------
dtrace: error on enabled probe ID 3 (ID 371: syscall::open:return): invalid address (0x7f7fffbd9ee0) in action #10 at DIF offset 12
: No such file or directory
dtrace: error on enabled probe ID 3 (ID 371: syscall::open:return): invalid address (0x7992e579394b) in action #10 at DIF offset 12
: No such file or directory
....
--------------------------------

. I used a bit DTrace  in the past, the problem appears to be related to the print of "arg0". Indeed:
. this works:
$> doas /usr/sbin/dtrace -n 'syscall::open:entry { printf(". open file - %s", execname); } '

. but this fails 
doas /usr/sbin/dtrace -n 'syscall::open:entry { printf("%s %s", execname, copyinstr(arg0)); } ' 
---- output ----------------------
dtrace: error on enabled probe ID 1 (ID 370: syscall::open:entry): invalid address (0x7f7ffffbaeb0) in action #2 at DIF offset 12
: No such file or directory
dtrace: error on enabled probe ID 1 (ID 370: syscall::open:entry): invalid address (0x7f7ffffba5e0) in action #2 at DIF offset 12
: No such file or directory
...
-----------------------------------






>Fix: