From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <musl-return-20271-ml=inbox.vuxu.org@lists.openwall.com>
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org
X-Spam-Level: 
X-Spam-Status: No, score=-2.9 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED,
	HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,
	RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,T_SCC_BODY_TEXT_LINE autolearn=ham
	autolearn_force=no version=3.4.4
Received: from second.openwall.net (second.openwall.net [193.110.157.125])
	by inbox.vuxu.org (Postfix) with SMTP id 5837A23D5C
	for <ml@inbox.vuxu.org>; Sun, 21 Jan 2024 13:06:28 +0100 (CET)
Received: (qmail 22163 invoked by uid 550); 21 Jan 2024 12:04:26 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
List-ID: <musl.lists.openwall.com>
Reply-To: musl@lists.openwall.com
Received: (qmail 22128 invoked from network); 21 Jan 2024 12:04:26 -0000
MIME-Version: 1.0
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dustri.org; s=key1;
	t=1705838775;
	h=from:from:reply-to:subject:subject:date:date:message-id:message-id:
	 to:to:cc:cc:mime-version:mime-version:content-type:content-type:
	 content-transfer-encoding:content-transfer-encoding:
	 in-reply-to:in-reply-to:references:references;
	bh=ObDCORSzPEQD278PV4dTAjVWPBYTWHIa1sK1RK6L9mo=;
	b=cQ1/oVs7FO+cxec0XD215qR0YaDSGBQvK9NPiBN8dMkncDDI/K3Y96uE8PGgta8613HQkO
	D2Kg1+sDiUDw3raB+tjgZ6lr/On4uO9pqxSZFjJUDq+0JcDtItkfgfHkjoNZILFhM7L2Wf
	ySvZKXucH9ZTofIZL6p/3jyht2R+qDyF/+xiVYjyGA4252Qb6PFmhijp6R7jve1YvwU5kC
	Km8IfNUiA33xVuMhKCWXYmmNhfWgVIIhAjgaht2e5tf9uSTDVb0uh0qOUX/e8hQmZ3K7xR
	D+lWX/ayMOUdBijMSzh6eIJwJry7mdjFlsWU8ex+EEJA8mzAc2UP+OPAcv8wDA==
Date: Sun, 21 Jan 2024 12:06:14 +0000
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers.
From: julien.voisin@dustri.org
Message-ID: <820837e29ea605142a934e672d670fbbd9d44cbd@dustri.org>
TLS-Required: No
To: "Rich Felker" <dalias@libc.org>
Cc: musl@lists.openwall.com
In-Reply-To: <20240121034301.GZ4163@brightrain.aerifal.cx>
References: <ec138086-c5b9-4ca2-9da5-bef8b14de27d@dustri.org>
 <20240109190726.GO4163@brightrain.aerifal.cx>
 <20240121034301.GZ4163@brightrain.aerifal.cx>
X-Migadu-Flow: FLOW_OUT
Subject: Re: [musl] Protect pthreads' mutexes against use-after-destroy

> Draft attached in case anyone wants to play with it. This could
> probably be something we could consider to adopt.

Couldn't a macro like `#define mutex_is_destroyed (!(m->_m_type & 8) && (=
m->_m_lock =3D=3D 0x3fffffff)` be
used instead? Or at least named constants instead of `8` and `0x3fffffff`=
.

Also, the code-style seems inconsistent:

```
+       if (own =3D=3D 0x3fffffff) {
+               /* Catch use-after-destroy */
+               if (!(type & 8)) a_crash();=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
+=20              return ENOTRECOVERABLE;
+       }
```

vs=20

```
+=20                      /* Catch use-after-destroy */
+                       if (own =3D=3D 0x3fffffff && !(type & 8)) a_crash=
();
                        return EPERM;
```

Both are the same check, yet only one has both conditions in a single `if=
`.