NetBSD Problem Report #52634

From campbell@mumble.net  Fri Oct 20 15:59:32 2017
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Date: Fri, 20 Oct 2017 16:02:27 +0000 (UTC)
From: Taylor R Campbell <riastradh@NetBSD.org>
Reply-To: Taylor R Campbell <riastradh@NetBSD.org>
To: gnats-bugs@gnats.NetBSD.org
Subject: possible unhandled spurious wakeup in posix_spawn
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>Number:         52634
>Category:       kern
>Synopsis:       possible unhandled spurious wakeup in posix_spawn
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    martin
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Oct 20 16:00:00 +0000 2017
>Closed-Date:    Sat Jun 27 17:25:29 +0000 2026
>Last-Modified:  Sat Jun 27 17:25:29 +0000 2026
>Originator:     Taylor R Campbell <riastradh@NetBSD.org>
>Release:        NetBSD-current
>Organization:
The NetBSD Foundation
>Environment:
any
>Description:

	do_posix_spawn calls cv_wait without looping on a test for a
	condition, which may cause it to return before the child is
	ready -- and potentially even to read and return an
	uninitialized error -- in the case of a spurious wakeup:

	https://nxr.netbsd.org/xref/src/sys/kern/kern_exec.c?r=1.448#2605

>How-To-Repeat:

	Code inspection.

>Fix:

	Yes, please!

>Release-Note:

>Audit-Trail:

Responsible-Changed-From-To: kern-bug-people->martin
Responsible-Changed-By: martin@NetBSD.org
Responsible-Changed-When: Fri, 20 Oct 2017 16:03:05 +0000
Responsible-Changed-Why:
take


From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/52634 CVS commit: src/sys/kern
Date: Sat, 15 Mar 2025 12:11:09 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Sat Mar 15 12:11:09 UTC 2025

 Modified Files:
 	src/sys/kern: kern_exec.c

 Log Message:
 posix_spawn(2): Fix race between parent and child.

 This was an embarrassing misuse of condition variables.

 PR kern/59175: posix_spawn hang, hanging other process too
 PR kern/52634: possible unhandled spurious wakeup in posix_spawn

 (This only resolves one of the symptoms wiz had in PR 59175; there is
 also another issue involved with p_vmspace and p_psstrp.)


 To generate a diff of this commit:
 cvs rdiff -u -r1.525 -r1.526 src/sys/kern/kern_exec.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->needs-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Sat, 15 Mar 2025 13:50:12 +0000
State-Changed-Why:
fixed in HEAD, needs pullup-9 and pullup-10

(This is not just a matter of spurious wakeups; it is also broken for
early wakeups.)


State-Changed-From-To: needs-pullups->pending-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Fri, 26 Jun 2026 03:46:12 +0000
State-Changed-Why:
pullup-9 #2015
pullup-10 #1283
fixed in HEAD before netbsd-11 branch


From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/52634 CVS commit: [netbsd-10] src/sys/kern
Date: Sat, 27 Jun 2026 17:21:06 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sat Jun 27 17:21:06 UTC 2026

 Modified Files:
 	src/sys/kern [netbsd-10]: kern_exec.c

 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #1283):

 	sys/kern/kern_exec.c: revision 1.526

 posix_spawn(2): Fix race between parent and child.

 This was an embarrassing misuse of condition variables.

 PR kern/59175: posix_spawn hang, hanging other process too
 PR kern/52634: possible unhandled spurious wakeup in posix_spawn
 (This only resolves one of the symptoms wiz had in PR 59175; there is
 also another issue involved with p_vmspace and p_psstrp.)


 To generate a diff of this commit:
 cvs rdiff -u -r1.518.4.3 -r1.518.4.4 src/sys/kern/kern_exec.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/52634 CVS commit: [netbsd-9] src/sys/kern
Date: Sat, 27 Jun 2026 17:22:27 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sat Jun 27 17:22:27 UTC 2026

 Modified Files:
 	src/sys/kern [netbsd-9]: kern_exec.c

 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #2015):

 	sys/kern/kern_exec.c: revision 1.526

 posix_spawn(2): Fix race between parent and child.

 This was an embarrassing misuse of condition variables.

 PR kern/59175: posix_spawn hang, hanging other process too
 PR kern/52634: possible unhandled spurious wakeup in posix_spawn
 (This only resolves one of the symptoms wiz had in PR 59175; there is
 also another issue involved with p_vmspace and p_psstrp.)


 To generate a diff of this commit:
 cvs rdiff -u -r1.478.2.3 -r1.478.2.4 src/sys/kern/kern_exec.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: pending-pullups->closed
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Sat, 27 Jun 2026 17:25:29 +0000
State-Changed-Why:
fixed in HEAD, pulled up to 11, 10, and 9


>Unformatted:

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