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 3B637C88E75 for ; Tue, 15 Sep 2026 16:33:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x6W4X-0006IQ-VS; Tue, 15 Sep 2026 12:31:54 -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 1x6W4N-00063B-4E for qemu-devel@nongnu.org; Tue, 15 Sep 2026 12:31:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x6W4K-0003u9-Fq for qemu-devel@nongnu.org; Tue, 15 Sep 2026 12:31:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1789489898; h=from:from:reply-to: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=X+GwKKNx6m5OM6MqSOp1FOXCkghAqwRgLLCpLbhxKas=; b=B7wowTkHJSRLTO3C+zumxzWIgrhUXr5SIbe3zQ8udDX9u1FwL/+8crjhBxSrvV14SuYIsJ tF6IkyghC5bzgeHrrc22hEe/F2Z/5w0LTmVCXsNeYelmWUAzGmbHqxck3KfpZ5kegYsxmO fG5MxN4sjUwZw6LIQy7ekriQDkZhxOE= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-693-Z3PC60uaM3q1UhdhD5ImXQ-1; Tue, 15 Sep 2026 12:31:36 -0400 X-MC-Unique: Z3PC60uaM3q1UhdhD5ImXQ-1 X-Mimecast-MFC-AGG-ID: Z3PC60uaM3q1UhdhD5ImXQ_1789489895 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9FA461955BC9; Tue, 15 Sep 2026 16:31:34 +0000 (UTC) Received: from redhat.com (headnet03.pony-001.prod.iad2.dc.redhat.com [10.2.32.114]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1BF1F426; Tue, 15 Sep 2026 16:31:31 +0000 (UTC) Date: Tue, 15 Sep 2026 17:31:28 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: =?utf-8?B?0J3QuNC60L7Qu9Cw0Lkg0JfQvtGA0LjQvQ==?= Cc: qemu-devel@nongnu.org, thuth@redhat.com, mst@redhat.com, stefanha@redhat.com, kwolf@redhat.com, marcandre.lureau@redhat.com, mark.cave-ayland@ilande.co.uk Subject: Re: [PATCH] hw/display/tcx: use memmove instead of memcpy for overlapping blit memory regions Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.4.0 (2026-06-19) X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Sep 15, 2026 at 07:20:46PM +0300, Николай Зорин wrote: > SWSA#34e3af79-c6c2-4ad2-986f-313c1ce28e5a ^^^^^^^^^ what is this ? I'm guessing it is a tag you're using for tracking issues, but if so, it should be removed before sending commits upstream. > > In `tcx_blit_writel()`, memory copying occurs within the same video RAM > buffers (`vram` and `vram24`) using source and destination offsets that > can potentially overlap during blit operations. > > Using `memcpy()` on overlapping memory regions triggers undefined behavior > according to the C standard. Depending on compiler optimizations, this > can lead to graphical artifacts, memory corruption, or unexpected > behavior in the guest system. > > Fix this by replacing `memcpy()` with `memmove()`, which explicitly > guarantees safe and correct behavior when memory regions overlap. > > Signed-off-by: Nikolay N Zorin > --- >  hw/display/tcx.c | 4 ++-- >  1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/display/tcx.c b/hw/display/tcx.c > index 2cfc1e8f..fb48a199 100644 > --- a/hw/display/tcx.c > +++ b/hw/display/tcx.c > @@ -587,9 +587,9 @@ static void tcx_blit_writel(void *opaque, hwaddr addr, >                  } >              } >          } else { > -            memcpy(&s->vram[addr], &s->vram[adsr], len); > +            memmove(&s->vram[addr], &s->vram[adsr], len); >              if (s->depth == 24) { > -                memcpy(&s->vram24[addr], &s->vram24[adsr], len * 4); > +                memmove(&s->vram24[addr], &s->vram24[adsr], len * 4); >              } >          } >          tcx_set_dirty(s, addr, len); > -- > 2.43.0 > > With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|