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From: Thorsten Glaser <tg@mirbsd.de>
To: musl@lists.openwall.com
Subject: Re: [musl] Potential bug in __res_msend_rc() wrt to union initialization.
Date: Tue, 19 Mar 2024 20:47:00 +0000 (UTC)	[thread overview]
Message-ID: <Pine.BSM.4.64L.2403192046020.21682@herc.mirbsd.org> (raw)
In-Reply-To: <20240319173930.57b8eb30@inria.fr>

Jₑₙₛ Gustedt dixit:

>seems to be to always put the biggest union member first, or to even
>add an artificial first one `char [size-of-the-union] __dummy;`, such
>that this is always 0-byte initialized if there is any initialization

But then you can just memset the union and then initialise any
known pointer members to NULL/nullptr manually afterwards in the
union’s member you actually need.

(IIRC, POSIX actively specifies the possible pointer members in
these structs for that reason.)

bye,
//mirabilos
-- 
15:41⎜<Lo-lan-do:#fusionforge> Somebody write a testsuite for helloworld :-)

  reply	other threads:[~2024-03-19 20:53 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-18 19:56 Mike Cui
2024-03-18 21:34 ` Rich Felker
2024-03-18 22:22   ` NRK
2024-03-18 22:39     ` [musl] Potential bug in __res_msend_rc() wrt to union initialisation Thorsten Glaser
2024-03-19  0:01     ` [musl] Potential bug in __res_msend_rc() wrt to union initialization Mike Cui
2024-03-19 13:18       ` Rich Felker
2024-03-19 15:04         ` Mike Cui
2024-03-19 15:42           ` Rich Felker
2024-03-19 15:55             ` Mike Cui
2024-03-19 16:08               ` Rich Felker
2024-03-19 16:39                 ` Jₑₙₛ Gustedt
2024-03-19 20:47                   ` Thorsten Glaser [this message]
2024-03-21 10:58                     ` Jₑₙₛ Gustedt
2024-03-21 16:41                       ` Thorsten Glaser
2024-03-19 21:04                   ` NRK
2024-03-19 21:36                     ` Rich Felker
2024-03-20 17:11                       ` NRK

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