NetBSD Problem Report #58510

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Date: Mon, 29 Jul 2024 01:47:59 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: experimental wg(4) lacks memory ordering between wg_count_dec and module unload
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>Number:         58510
>Category:       kern
>Synopsis:       experimental wg(4) lacks memory ordering between wg_count_dec and module unload
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          needs-pullups
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 29 01:50:00 +0000 2024
>Closed-Date:    
>Last-Modified:  Mon Jul 29 02:40:20 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current, 10
>Organization:
The wgunload Foundation
>Environment:
>Description:
All memory operations in wg_clone_destroy program-before wg_count_dec() must (globally) happen-before module unload.

However, although wgdetach (which is called by MODULE_CMD_FINI) checks wg_count program-before module unload, there are no memory barriers to guarantee this happens-before ordering.
>How-To-Repeat:
code inspection
>Fix:
membar_release before atomic_dec_uint_nv in wg_count_dec
atomic_load_acquire(&wg_count) in wgdetach

>Release-Note:

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/58510 CVS commit: src/sys/net
Date: Mon, 29 Jul 2024 02:34:27 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Mon Jul 29 02:34:27 UTC 2024

 Modified Files:
 	src/sys/net: if_wg.c

 Log Message:
 wg(4): Fix memory ordering in detach.

 PR kern/58510: experimental wg(4) lacks memory ordering between
 wg_count_dec and module unload


 To generate a diff of this commit:
 cvs rdiff -u -r1.117 -r1.118 src/sys/net/if_wg.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: Mon, 29 Jul 2024 02:40:20 +0000
State-Changed-Why:
fixed in HEAD, needs pullup-10


>Unformatted:

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