Date: Fri, 16 Jul 1999 13:24:07 -0700 (PDT) From: ambrisko@whistle.com To: freebsd-gnats-submit@freebsd.org Subject: kern/12669: SA_NOCLDWAIT not cleared on exec Message-ID: <19990716202407.3937F14CFD@hub.freebsd.org>
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>Number: 12669
>Category: kern
>Synopsis: SA_NOCLDWAIT not cleared on exec
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Jul 16 13:30:00 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator: Doug Ambrisko
>Release: 4-current
>Organization:
Whistle
>Environment:
FreeBSD 770z.whistle.com 4.0-CURRENT FreeBSD 4.0-CURRENT #6: Thu Jul 15 19:31:19 PDT 1999 ambrisko@770z.whistle.com:/usr/home/ambrisko/current/usr/src/sys.foo/compile/THINK i386
>Description:
I found a bug in FreeBSB with an old perl script that sets
$SIG{"CHLD"}="IGNORE". It seems to have broke ever since
SA_NOCLDWAIT has been implemented. The issue seems that
SA_NOCLDWAIT should be reset after exec so some /bin/sh commands
then hang. This is was Solaris apparently does so everything
works fine on Solaris even with pthread.
Note this is still broken for libc_r, however, on Solaris
it works fine with pthreads. I will investigate that later.
>How-To-Repeat:
Sample bug:
perl -e '$SIG{"CHLD"}="IGNORE"; system ("echo hello | echo hang");'
C version:
begin 664 bug.tgz
M'XL(`&%6CS<``^V6;6_:,!"`^9K\BA-;:6`4DD#3:8Q)#*JN6E\FJ+8OE9";
M.(E%2!`V;=':_[YS0J!TZSIM@NZ#'REQ?&??G<_QRRD949]%M+!!+--TG"84
M`&S3=F2)F(L2L4P+P#EH-IQ]V[(:*+`<:[\`YB:#RIEQ0:8`!3*^FC(^2IYJ
M=Q-2&FTCH.VBZ]UN.W!=72=1]$[7IF/8\T%P(1];UUX;IYW/AV596ZN@JE:7
MPI<>@.*?P"FLN1OV\<SZMQN.F:]_RS8/Y/JWG`.U_K?!*Q:[T<RC\)[/>5W,
M)Y37P@_Z2CR+&1?>NHRS(":1E.ECPF*C_%W7)LP;"AC/A_C1#JC`PBBW<CF^
M\9O%`N<;$RYFO*7KFAO*U%>XF+(X0$'60EI/VH/CH^ZGDQ[V0O7,3<7$%2R)
M`8LJ)/A&Y77"/*B$)/8B.I6=AL='9RT==`WU-4Z&"Q6T8?$E+;*`CB=BSJDP
M2HMV8\)',MY%U8](P+&3^5ATUX9!9]@_'%QT^A<MJ%=@\+7?K$*SUGCS<="#
M2AU],Q^,=!C0QN;92*!4@F4PJ52&6M:U_!C\A9NS\^Y)[UOG^**UM)GE(+->
MA5*:BY),1EE:W;/0H#;!?`K?*![VS_N7<1&'M7"QU'PA4XJIQ@F(`[KFZ5+`
MC@<[;V_S!PU4LVFM/HRP]+#3FJ:ZGM$G7%]1/YG^N>OD:=]KJF5MX5WFS;A&
M5R.C+']3[;<I7$;[4[C$%SAOTL[&0]:T&\+PQ\S6B13<TXC3OPF^&[+(RU--
M;ZF[A>#I+09OIF'+%9VN7US>[2)UPP1"&D4)W(%+1+&UTJ5W"5M*\M`'N"T+
MV,5=2=`Q[/!=&5S67-K.Y,9*D/?K)3'-N^UF/_\JI'MU77F$3/NF+P#/G/]6
M>N?/SG^S83:EQ&Y:ZOS?!B]Y_JOS?F/G_6H_O!39(;#IC5]MK0J%0J%0*!0*
7A4*A4"@4"H5"H5#\-_P`7^B?80`H``#G
`
end
Machine without patch for resetting SA_NOCLDWAIT after exec.
770z% gmake
rm -f tst tst2
gmake tst
gmake[1]: Entering directory `/usr/home/ambrisko'
gcc tst.c -o tst
gmake[1]: Leaving directory `/usr/home/ambrisko'
gmake tst2
gmake[1]: Entering directory `/usr/home/ambrisko'
gcc tst2.c -o tst2
gmake[1]: Leaving directory `/usr/home/ambrisko'
./tst
Parent change SA_NOCLDWAIT 988 20 22 0
Parent before SA_NOCLDWAIT 988 0 2 0
Child before exec SA_NOCLDWAIT 988 20 22 0
Parent after fork SA_NOCLDWAIT 988 20 22 0
Start 'system ./tst2'
Child SA_NOCLDWAIT 991 20 22 0
[Then hangs]
Machine with patch for resetting SA_NOCLDWAIT after exec.
dhcp2% make
rm -f tst tst2
make tst
gcc -O -pipe tst.c -o tst
make tst2
gcc -O -pipe tst2.c -o tst2
./tst
Parent change SA_NOCLDWAIT 284 20 22 0
Parent before SA_NOCLDWAIT 284 0 2 0
Child before exec SA_NOCLDWAIT 284 20 22 0
Parent after fork SA_NOCLDWAIT 284 20 22 0
Start 'system ./tst2'
Child SA_NOCLDWAIT 287 0 2 0
Done 'system'
dhcp2%
On Solaris 5.7
% make
rm -f tst tst2
make tst
make[1]: Entering directory `/a/207.76.205.244/root/usr/home/ambrisko'
gcc tst.c -o tst
make[1]: Leaving directory `/a/207.76.205.244/root/usr/home/ambrisko'
make tst2
make[1]: Entering directory `/a/207.76.205.244/root/usr/home/ambrisko'
gcc tst2.c -o tst2
make[1]: Leaving directory `/a/207.76.205.244/root/usr/home/ambrisko'
./tst
Parent change SA_NOCLDWAIT 26241 10000 10004 effffb30
Parent before SA_NOCLDWAIT 26241 0 20000 effffb30
Child before exec SA_NOCLDWAIT 26241 10000 10000 effffb30
Parent after fork SA_NOCLDWAIT 26241 10000 10000 effffb30
Start 'system ./tst2'
Child SA_NOCLDWAIT 26244 0 20000 effffb38
Done 'system'
%
>Fix:
Index: kern_sig.c
===================================================================
RCS file: /cvs/freebsd/src/sys/kern/kern_sig.c,v
retrieving revision 1.57
diff -r1.57 kern_sig.c
300a301,304
> /*
> * Reset no zombies if child dies flag as Solaris does.
> */
> p->p_procsig->ps_flag &= ~P_NOCLDWAIT;
>Release-Note:
>Audit-Trail:
>Unformatted:
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