From nobody Thu May 14 08:17:34 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6303C433F5 for ; Tue, 19 Apr 2022 13:56:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344653AbiDSN70 (ORCPT ); Tue, 19 Apr 2022 09:59:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344626AbiDSN7P (ORCPT ); Tue, 19 Apr 2022 09:59:15 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 72ABA38BEA for ; Tue, 19 Apr 2022 06:56:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650376591; 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; bh=y7hLPCx+q8pxXoxgpMGPpDODmiVdYzBrDyMDcRztRug=; b=Ryb5pplSP7KNp+2HQ3DXOTgEqjend0WmocfSQQi0SMRr50cxuuNMZ1XA7mEWBFYbc8c/F5 sIYy8K6vk5p07GGlgglG7w/0mAfvR5hGHebTGyH0zw5duinsAj12rzB/M+VmyCnjCerUy0 rK2atywuEFgUIl/Ut466POpjOs0kEFg= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-62-O6FRTvRaM66q_8MJxIYw0g-1; Tue, 19 Apr 2022 09:56:25 -0400 X-MC-Unique: O6FRTvRaM66q_8MJxIYw0g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0C0E11C01700; Tue, 19 Apr 2022 13:56:25 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F1741C54184; Tue, 19 Apr 2022 13:56:24 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 23JDuOuf020642; Tue, 19 Apr 2022 09:56:24 -0400 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 23JDuNCK020638; Tue, 19 Apr 2022 09:56:23 -0400 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Tue, 19 Apr 2022 09:56:23 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] x86: __memcpy_flushcache: fix wrong alignment if size > 2^32 Message-ID: User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: TEXT/PLAIN; charset="utf-8" The first "if" condition in __memcpy_flushcache is supposed to align the "dest" variable to 8 bytes and copy data up to this alignment. However, this condition may misbehave if "size" is greater than 4GiB. The statement min_t(unsigned, size, ALIGN(dest, 8) - dest); casts both arguments to unsigned int and selects the smaller one. However, the cast truncates high bits in "size" and it results in misbehavior. For example: suppose that size =3D=3D 0x100000001, dest =3D=3D 0x200000002 min_t(unsigned, size, ALIGN(dest, 8) - dest) =3D=3D min_t(0x1, 0xe) =3D=3D= 0x1; ... dest +=3D 0x1; so we copy just one byte "and" dest remains unaligned. This patch fixes the bug by replacing unsigned with size_t. Signed-off-by: Mikulas Patocka --- arch/x86/lib/usercopy_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/arch/x86/lib/usercopy_64.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-2.6.orig/arch/x86/lib/usercopy_64.c +++ linux-2.6/arch/x86/lib/usercopy_64.c @@ -119,7 +119,7 @@ void __memcpy_flushcache(void *_dst, con =20 /* cache copy and flush to align dest */ if (!IS_ALIGNED(dest, 8)) { - unsigned len =3D min_t(unsigned, size, ALIGN(dest, 8) - dest); + size_t len =3D min_t(size_t, size, ALIGN(dest, 8) - dest); =20 memcpy((void *) dest, (void *) source, len); clean_cache_range((void *) dest, len);