NetBSD Problem Report #59225

From www@netbsd.org  Thu Mar 27 00:43:52 2025
Return-Path: <www@netbsd.org>
Received: from mail.netbsd.org (mail.netbsd.org [199.233.217.200])
	(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
	 key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256
	 client-signature RSA-PSS (2048 bits) client-digest SHA256)
	(Client CN "mail.NetBSD.org", Issuer "mail.NetBSD.org CA" (not verified))
	by mollari.NetBSD.org (Postfix) with ESMTPS id 40C641A9239
	for <gnats-bugs@gnats.NetBSD.org>; Thu, 27 Mar 2025 00:43:52 +0000 (UTC)
Message-Id: <20250327004351.12D0B1A923D@mollari.NetBSD.org>
Date: Thu, 27 Mar 2025 00:43:51 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: sysconf(3) is not async-signal-safe for some inputs
X-Send-Pr-Version: www-1.0

>Number:         59225
>Category:       lib
>Synopsis:       sysconf(3) is not async-signal-safe for some inputs
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Mar 27 00:45:00 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current, 10, 9, ...
>Organization:
The SignalBSD Sysconfiguration
>Environment:
>Description:
For certain inputs, such as _SC_AIO_LISTIO_MAX, sysconf(3) internally calls sysctlgetmibinfo(3), which is not async-signal-safe (see PR lib/59147: sysctl: bounded-memory lookups by name <https://gnats.NetBSD.org/59147>).
>How-To-Repeat:
1. code inspection
2. call sysconf(3) from a signal handler that interrupts malloc(3)
>Fix:
Either:

1. Assign static numbers to all the sysctl nodes that sysconf(3) might query.
2. Fix PR 59147, either making sysctlgetmibinfo(3) async-signal-safe or adding an alternative that is async-signal-safe at the cost of lookup cache performance.

Home	PR Database Search