[next] xen: privcmd: Replace zero-length array with flex-array member and use __counted_by
| Message ID | ZVZlg3tPMPCRdteh@work |
|---|---|
| State | New |
| Headers |
Return-Path: <linux-kernel-owner@vger.kernel.org>
Delivered-To: ouuuleilei@gmail.com
Received: by 2002:a59:9910:0:b0:403:3b70:6f57 with SMTP id i16csp44954vqn;
Thu, 16 Nov 2023 10:56:38 -0800 (PST)
X-Google-Smtp-Source:
AGHT+IESfzTzByO1A90aiFIvFNfe2p0zEXDAabk9kASk1Go9Ri1iwfCoiFM4VYgG/T7bRBIwPdjJ
X-Received: by 2002:a05:6a21:9992:b0:186:bd68:fa74 with SMTP id
ve18-20020a056a21999200b00186bd68fa74mr12582379pzb.22.1700160997843;
Thu, 16 Nov 2023 10:56:37 -0800 (PST)
ARC-Seal: i=1; a=rsa-sha256; t=1700160997; cv=none;
d=google.com; s=arc-20160816;
b=0YDS8bw6E1n7hliC+baEWgaogDJ5DXgZDUV+kyWKf4CWa4q5yHRHkfX/L57Hxni62+
3Osu/eNZEzp2S+H6ZAVtpTxi7z+dAyASj7D6ffTWZhDAXPa02b2lJVr/jrnHfYeJsAJV
ezJND7DLiKVlERySkqEcEfFtDHqI9Brtmc9aJyv4YKoH0qNiu/5Zb5s3JlbERz81koAX
N6ngNZaYsp5JYqJKLEOHFDyhOYyVae6GbndYuFpKNrwH/PPHRyOHBI97bKeSrvocDVgm
3DbAZMdqSZFUh94HMJ16EQ3QrmoLQrQ/Th9I/K7ZNl39SEx6npuR93/wmU2kljyZoYco
QC2g==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com;
s=arc-20160816;
h=list-id:precedence:content-disposition:mime-version:message-id
:subject:cc:to:from:date:dkim-signature;
bh=OCPJFEqpeLxujmn8gJLKB3zbLNlfUGdZvBYYuSiWDJ8=;
fh=grvoduVzbCjvQHNuY8TNqZyALqbAi7v/eKkAflEVkYI=;
b=WW2zHrVB6bjXlbrkU4cG9iiwyH/2Wt2lUKKGJQT2cM/Aju0/Jn+TjND5Qx9Um5Yfsl
9VK7NlMi8d8zNBiKdLj+J3tXnQXwtxMZF/hAQeZyUbtXVVbf5Oz3LRSX5PVIOUMBpe4a
T2I96aoEYzTsSity1gPdUvcRxhVVOKGRiMsJUddzvQHNPXsPwCm9AHtBQOIcerAH0Ak1
VVWo910eSus2eqWwB7vst1JsycxWqPDMQWHDYbpCyOLPe+oBqk6+279YsOXREMIsMBMe
NDRGfmLJEwMciXjLep1qFCp5aILPUi9WFyr7q2/N4zQAt0KveR2tmeWIfDZ/PpxBtXcd
Pfag==
ARC-Authentication-Results: i=1; mx.google.com;
dkim=pass header.i=@kernel.org header.s=k20201202 header.b=Q2KeOstZ;
spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org
designates 23.128.96.37 as permitted sender)
smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org
Received: from snail.vger.email (snail.vger.email. [23.128.96.37])
by mx.google.com with ESMTPS id
bn6-20020a056a02030600b00578b8d202b0si60548pgb.536.2023.11.16.10.56.37
(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
Thu, 16 Nov 2023 10:56:37 -0800 (PST)
Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org
designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
Authentication-Results: mx.google.com;
dkim=pass header.i=@kernel.org header.s=k20201202 header.b=Q2KeOstZ;
spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org
designates 23.128.96.37 as permitted sender)
smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org
Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0])
by snail.vger.email (Postfix) with ESMTP id DBDF781DD7C1;
Thu, 16 Nov 2023 10:56:36 -0800 (PST)
X-Virus-Status: Clean
X-Virus-Scanned: clamav-milter 0.103.11 at snail.vger.email
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
id S229534AbjKPSzH (ORCPT <rfc822;jaysivo@gmail.com> + 30 others);
Thu, 16 Nov 2023 13:55:07 -0500
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35502 "EHLO
lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
with ESMTP id S229448AbjKPSzG (ORCPT
<rfc822;linux-kernel@vger.kernel.org>);
Thu, 16 Nov 2023 13:55:06 -0500
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A7FC1A8
for <linux-kernel@vger.kernel.org>;
Thu, 16 Nov 2023 10:55:03 -0800 (PST)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BBB8C433C8;
Thu, 16 Nov 2023 18:55:01 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;
s=k20201202; t=1700160902;
bh=JwQgKXdyVFHDeYy2JqIrcrbfOB3OycZsBTQgBU7qjPM=;
h=Date:From:To:Cc:Subject:From;
b=Q2KeOstZqpSdN4JhKTSNmJecY3BmKrmxV0TKxlDYtF5gv7UBoA9ki8l+3oU7WT0Hx
SGmSc3VfEncIDsy7g1gUdu/dUurdmxWoNKqVqXpNG0JIQn/9CRKtLj4EZby3gR0ebM
W29DzH+9f5rXc4ky/j82PuHjBZxanaXp2OXpLgfdOeYwEyc8H6InT7BIuTjYwI2twZ
K2Q59QirBuKsjjD1uHuCUq6Vt0CT0Ut1+Mc3R70pFEkwWmeLddoRJdAqfYUx+Un6j7
onTVWGPMm6W16RlorLGNo7T/80qIpz+vuwThsSHkscF6lBwIA6x+UPnUOlCQ+Gw8al
9yTiFS6TTIGSg==
Date: Thu, 16 Nov 2023 12:54:59 -0600
From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org
Subject: [PATCH][next] xen: privcmd: Replace zero-length array with
flex-array member and use __counted_by
Message-ID: <ZVZlg3tPMPCRdteh@work>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,
RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE
autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test,
not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]);
Thu, 16 Nov 2023 10:56:36 -0800 (PST)
X-getmail-retrieved-from-mailbox: INBOX
X-GMAIL-THRID: 1782748018210975005
X-GMAIL-MSGID: 1782748018210975005
|
| Series |
[next] xen: privcmd: Replace zero-length array with flex-array member and use __counted_by
|
|
Commit Message
Gustavo A. R. Silva
Nov. 16, 2023, 6:54 p.m. UTC
Fake flexible arrays (zero-length and one-element arrays) are deprecated,
and should be replaced by flexible-array members. So, replace
zero-length array with a flexible-array member in `struct
privcmd_kernel_ioreq`.
Also annotate array `ports` with `__counted_by()` to prepare for the
coming implementation by GCC and Clang of the `__counted_by` attribute.
Flexible array members annotated with `__counted_by` can have their
accesses bounds-checked at run-time via `CONFIG_UBSAN_BOUNDS` (for array
indexing) and `CONFIG_FORTIFY_SOURCE` (for strcpy/memcpy-family functions).
This fixes multiple -Warray-bounds warnings:
drivers/xen/privcmd.c:1239:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=]
drivers/xen/privcmd.c:1240:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=]
drivers/xen/privcmd.c:1241:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=]
drivers/xen/privcmd.c:1245:33: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=]
drivers/xen/privcmd.c:1258:67: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=]
This results in no differences in binary output.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/xen/privcmd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Comments
On Thu, Nov 16, 2023 at 12:54:59PM -0600, Gustavo A. R. Silva wrote: > Fake flexible arrays (zero-length and one-element arrays) are deprecated, > and should be replaced by flexible-array members. So, replace > zero-length array with a flexible-array member in `struct > privcmd_kernel_ioreq`. > > Also annotate array `ports` with `__counted_by()` to prepare for the > coming implementation by GCC and Clang of the `__counted_by` attribute. > Flexible array members annotated with `__counted_by` can have their > accesses bounds-checked at run-time via `CONFIG_UBSAN_BOUNDS` (for array > indexing) and `CONFIG_FORTIFY_SOURCE` (for strcpy/memcpy-family functions). > > This fixes multiple -Warray-bounds warnings: > drivers/xen/privcmd.c:1239:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1240:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1241:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1245:33: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1258:67: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > > This results in no differences in binary output. > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Looks right to me. I can see the allocation: size = struct_size(kioreq, ports, ioeventfd->vcpus); kioreq = kzalloc(size, GFP_KERNEL); if (!kioreq) return ERR_PTR(-ENOMEM); kioreq->dom = ioeventfd->dom; kioreq->vcpus = ioeventfd->vcpus; Reviewed-by: Kees Cook <keescook@chromium.org>
On 11/16/23 15:08, Kees Cook wrote: > On Thu, Nov 16, 2023 at 12:54:59PM -0600, Gustavo A. R. Silva wrote: >> Fake flexible arrays (zero-length and one-element arrays) are deprecated, >> and should be replaced by flexible-array members. So, replace >> zero-length array with a flexible-array member in `struct >> privcmd_kernel_ioreq`. >> >> Also annotate array `ports` with `__counted_by()` to prepare for the >> coming implementation by GCC and Clang of the `__counted_by` attribute. >> Flexible array members annotated with `__counted_by` can have their >> accesses bounds-checked at run-time via `CONFIG_UBSAN_BOUNDS` (for array >> indexing) and `CONFIG_FORTIFY_SOURCE` (for strcpy/memcpy-family functions). >> >> This fixes multiple -Warray-bounds warnings: >> drivers/xen/privcmd.c:1239:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] >> drivers/xen/privcmd.c:1240:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] >> drivers/xen/privcmd.c:1241:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] >> drivers/xen/privcmd.c:1245:33: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] >> drivers/xen/privcmd.c:1258:67: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] >> >> This results in no differences in binary output. >> >> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > > Looks right to me. I can see the allocation: Yep, I always check for that; in particular, the 'counter' assignment. :) Do you want me to mention it in the changelog text? > > size = struct_size(kioreq, ports, ioeventfd->vcpus); > kioreq = kzalloc(size, GFP_KERNEL); > if (!kioreq) > return ERR_PTR(-ENOMEM); > > kioreq->dom = ioeventfd->dom; > kioreq->vcpus = ioeventfd->vcpus; > > > Reviewed-by: Kees Cook <keescook@chromium.org> Thanks! -- Gustavo
On 16.11.23 19:54, Gustavo A. R. Silva wrote: > Fake flexible arrays (zero-length and one-element arrays) are deprecated, > and should be replaced by flexible-array members. So, replace > zero-length array with a flexible-array member in `struct > privcmd_kernel_ioreq`. > > Also annotate array `ports` with `__counted_by()` to prepare for the > coming implementation by GCC and Clang of the `__counted_by` attribute. > Flexible array members annotated with `__counted_by` can have their > accesses bounds-checked at run-time via `CONFIG_UBSAN_BOUNDS` (for array > indexing) and `CONFIG_FORTIFY_SOURCE` (for strcpy/memcpy-family functions). > > This fixes multiple -Warray-bounds warnings: > drivers/xen/privcmd.c:1239:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1240:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1241:30: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1245:33: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > drivers/xen/privcmd.c:1258:67: warning: array subscript i is outside array bounds of 'struct ioreq_port[0]' [-Warray-bounds=] > > This results in no differences in binary output. > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 1ce7f3c7a950..0eb337a8ec0f 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -1115,7 +1115,7 @@ struct privcmd_kernel_ioreq { spinlock_t lock; /* Protects ioeventfds list */ struct list_head ioeventfds; struct list_head list; - struct ioreq_port ports[0]; + struct ioreq_port ports[] __counted_by(vcpus); }; static irqreturn_t ioeventfd_interrupt(int irq, void *dev_id)