From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D1F63C43458 for ; Wed, 1 Jul 2026 05:17:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wenJu-0002Oc-3h; Wed, 01 Jul 2026 01:17:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wenJo-0002Nr-VT for qemu-devel@nongnu.org; Wed, 01 Jul 2026 01:17:05 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wenJm-0004u3-89 for qemu-devel@nongnu.org; Wed, 01 Jul 2026 01:17:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782883020; 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: in-reply-to:in-reply-to:references:references; bh=peWTpTg7JqFAW0LkxxYWDjYDZtHG8zrUND5SPB98CHc=; b=JILnkAIv7FpRW+KvoNkCMIfh4hCr5WY/5Dw6FYMw+znJ1zll8/6dQgTN/7jgIv44CH04dF ojS4p8leqCCivzSWlS3K12n4WsdKh2dLdP/vlId8axzwOoosTt39Zr+Ydqkl+g17Zzf0fr rM3mVWHywtxEsKaj2QtLLmoI5xjFPkQ= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-554-iTcLylwGORm4VX27-UsSdQ-1; Wed, 01 Jul 2026 01:16:59 -0400 X-MC-Unique: iTcLylwGORm4VX27-UsSdQ-1 X-Mimecast-MFC-AGG-ID: iTcLylwGORm4VX27-UsSdQ_1782883018 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1DB28184A0B0; Wed, 1 Jul 2026 05:16:58 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.4]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 893891800586; Wed, 1 Jul 2026 05:16:57 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id C5D8621E6920; Wed, 01 Jul 2026 07:16:54 +0200 (CEST) From: Markus Armbruster To: "Christian S. Lima" Cc: qemu-devel@nongnu.org, Laurent Vivier Subject: Re: [PATCH v2] disas: converts malloc to g_new0 In-Reply-To: <20260630223159.68737-1-christianslima@proton.me> (Christian S. Lima's message of "Tue, 30 Jun 2026 22:32:04 +0000") References: <20260630223159.68737-1-christianslima@proton.me> Date: Wed, 01 Jul 2026 07:16:54 +0200 Message-ID: <87echnwapl.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org "Christian S. Lima" writes: > Following the qemu coding style change from malloc to g_new0, the > advantages are that g_new0 catch multiplication overflowing size_t, > allows for better detection of type errors because it returns the type > itself and initialize memory with zeros to detect if something go wrong. In general, just-in-case zero-initialization won't detect anything, it just converts unpredictable bad behavior to predictable bad behavior. In this case, it does exactly nothing, as we'll see below. > > Signed-off-by: Christian S. Lima > --- > Changes in v2: > - Change from g_malloc0 to g_new0 > --- > disas/m68k.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/disas/m68k.c b/disas/m68k.c > index 800b4145ac..c3571783b0 100644 > --- a/disas/m68k.c > +++ b/disas/m68k.c > @@ -1887,8 +1887,7 @@ print_insn_m68k (bfd_vma memaddr, disassemble_info *info) > > /* Then create a sorted table of pointers > that point into the unsorted table. */ > - opc_pointer[0] = malloc (sizeof (struct m68k_opcode *) > - * m68k_numopcodes); > + opc_pointer[0] = g_new0(const struct m68k_opcode *, m68k_numopcodes); > opcodes[0] = opc_pointer[0]; > > for (i = 1; i < 16; i++) { opc_pointer[i] = opc_pointer[i - 1] + numopcodes[i - 1]; opcodes[i] = opc_pointer[i]; } This obviously overwrites every single bit in opc_pointer[], i.e. the switch from allocating uninitialized to zero-initialzed memory is a complete waste. I'd use g_new(). Up to the maintainer. Either way, Reviewed-by: Markus Armbruster