kern/80130: [patch] sigprocmask erronously cleared on
fork(5-STABLE and later)
David Xu
davidxu at freebsd.org
Wed Apr 20 01:40:16 PDT 2005
The following reply was made to PR kern/80130; it has been noted by GNATS.
From: David Xu <davidxu at freebsd.org>
To: Kostik Belousov <konstantin.belousov at zoral.com.ua>
Cc: freebsd-gnats-submit at freebsd.org
Subject: Re: kern/80130: [patch] sigprocmask erronously cleared on fork (5-STABLE
and later)
Date: Wed, 20 Apr 2005 16:32:58 +0800
Kostik Belousov wrote:
>>Number: 80130
>>Category: kern
>>Synopsis: [patch] sigprocmask erronously cleared on fork (5-STABLE and later)
>>Confidential: no
>>Severity: serious
>>Priority: medium
>>Responsible: freebsd-bugs
>>State: open
>>Quarter:
>>Keywords:
>>Date-Required:
>>Class: sw-bug
>>Submitter-Id: current-users
>>Arrival-Date: Wed Apr 20 07:40:02 GMT 2005
>>Closed-Date:
>>Last-Modified:
>>Originator: Kostik Belousov
>>Release: 5-STABLE
>>Organization:
>>Environment:
>>
>>
>FreeBSD deviant.zoral.local 5.4-STABLE FreeBSD 5.4-STABLE #16: Tue Apr 12 11:06:01 EEST 2005 root at deviant.zoral.local:/usr/obj/usr/src/sys/DEVIANT i386
>
>
>>Description:
>>
>>
> After fork(), the 5-STABLE system sets the child process
>blocked signal mask to 0 (let us account single-threaded processes only). I was under impression that signal mask shall be inherited by the child process (according to SUSv3 and man fork). Inheritance _was_ the behaviour of 4-STABLE (there, p_sigmask belongs to struct proc and placed in the copied-on-fork part of the structure) and also seen on other UNIXes (e.g. Solaris).
>
>It seems that needs of thread_schedule_upcall() to zero sigmask interfere with the needs of the fork1(). I propose the trivial patch (against 5-STABLE) to fix the problems. It handles td_sigmask in the way similar to td_sigstk, that is also zeroed on _upcall(), as was done by davidxu at kern/kern_fork.c:1.209 rev.
>
>
>>How-To-Repeat:
>>
>>
>I send the letter to the freebsd-hackers at Apr 12, 2005 with the program that shows the problem, see
>
>http://lists.freebsd.org/pipermail/freebsd-hackers/2005-April/011513.html
>
>
>
>
>>Fix:
>>
>>
>Index: kern/kern_fork.c
>===================================================================
>RCS file: /usr/local/arch/ncvs/src/sys/kern/kern_fork.c,v
>retrieving revision 1.234.2.8
>diff -U3 -r1.234.2.8 kern_fork.c
>--- kern/kern_fork.c 27 Feb 2005 02:36:39 -0000 1.234.2.8
>+++ kern/kern_fork.c 20 Apr 2005 07:27:00 -0000
>@@ -472,6 +472,7 @@
> __rangeof(struct ksegrp, kg_startcopy, kg_endcopy));
>
> td2->td_sigstk = td->td_sigstk;
>+ td2->td_sigmask = td->td_sigmask;
>
> /*
> * Duplicate sub-structures as needed.
>
>
>
>>Release-Note:
>>Audit-Trail:
>>Unformatted:
>>
>>
The bug is also in -CURRENT. :(
David Xu
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