From patchwork Wed Aug 9 21:02:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13348509 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 07654C001B0 for ; Wed, 9 Aug 2023 21:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233193AbjHIVEg (ORCPT ); Wed, 9 Aug 2023 17:04:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233153AbjHIVEa (ORCPT ); Wed, 9 Aug 2023 17:04:30 -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 ESMTPS id 823A71BD9 for ; Wed, 9 Aug 2023 14:03:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691615023; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9Dj3+t39K/qBj5MrzSksnLCUG1VrR0qcfWhwfuxcrlk=; b=Gku1CW8a5Ktaq+W2jv5V5ntYYIZTCQd6clONwxXQgMobAeWB23DeYBtZuY0zSMktpJuWyd CeKLiZqLcPX3WIWj7jaK65Y3sa1pmLgllIhM48uTQ/5+MZQslmhqfjMpPhOtQbrX4tpPZz 9D5CdwtihBxAxum7vZRjLwY/jfGTh2k= Received: from mimecast-mx02.redhat.com (66.187.233.73 [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-696-l9RuCBQtNjyNy_v5wdxC-Q-1; Wed, 09 Aug 2023 17:03:39 -0400 X-MC-Unique: l9RuCBQtNjyNy_v5wdxC-Q-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 31D3B2999B26; Wed, 9 Aug 2023 21:03:39 +0000 (UTC) Received: from localhost (unknown [10.39.192.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8AC59C15BAE; Wed, 9 Aug 2023 21:03:38 +0000 (UTC) From: Stefan Hajnoczi To: kvm@vger.kernel.org Cc: Jason Gunthorpe , "Tian, Kevin" , linux-kernel@vger.kernel.org, Alex Williamson , Stefan Hajnoczi Subject: [PATCH 3/4] vfio: use __aligned_u64 in struct vfio_iommu_type1_info Date: Wed, 9 Aug 2023 17:02:47 -0400 Message-ID: <20230809210248.2898981-4-stefanha@redhat.com> In-Reply-To: <20230809210248.2898981-1-stefanha@redhat.com> References: <20230809210248.2898981-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The memory layout of struct vfio_iommu_type1_info is architecture-dependent due to a u64 field and a struct size that is not a multiple of 8 bytes: - On x86_64 the struct size is padded to a multiple of 8 bytes. - On x32 the struct size is only a multiple of 4 bytes, not 8. - Other architectures may vary. Use __aligned_u64 to make memory layout consistent. This reduces the chance of holes that result in an information leak and the chance that 32-bit userspace on a 64-bit kernel breakage. This patch increases the struct size on x32 but this is safe because of the struct's argsz field. The kernel may grow the struct as long as it still supports smaller argsz values from userspace (e.g. applications compiled against older kernel headers). Suggested-by: Jason Gunthorpe Signed-off-by: Stefan Hajnoczi Reviewed-by: Jason Gunthorpe --- include/uapi/linux/vfio.h | 3 ++- drivers/vfio/vfio_iommu_type1.c | 11 ++--------- 2 files changed, 4 insertions(+), 10 deletions(-) diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 45db62d74064..0b5786ec50d8 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1303,8 +1303,9 @@ struct vfio_iommu_type1_info { __u32 flags; #define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */ #define VFIO_IOMMU_INFO_CAPS (1 << 1) /* Info supports caps */ - __u64 iova_pgsizes; /* Bitmap of supported page sizes */ + __aligned_u64 iova_pgsizes; /* Bitmap of supported page sizes */ __u32 cap_offset; /* Offset within info struct of first cap */ + __u32 reserved; }; /* diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index ebe0ad31d0b0..f51159a7a4de 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -2762,27 +2762,20 @@ static int vfio_iommu_dma_avail_build_caps(struct vfio_iommu *iommu, static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, unsigned long arg) { - struct vfio_iommu_type1_info info; + struct vfio_iommu_type1_info info = {}; unsigned long minsz; struct vfio_info_cap caps = { .buf = NULL, .size = 0 }; - unsigned long capsz; int ret; minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes); - /* For backward compatibility, cannot require this */ - capsz = offsetofend(struct vfio_iommu_type1_info, cap_offset); - if (copy_from_user(&info, (void __user *)arg, minsz)) return -EFAULT; if (info.argsz < minsz) return -EINVAL; - if (info.argsz >= capsz) { - minsz = capsz; - info.cap_offset = 0; /* output, no-recopy necessary */ - } + minsz = min_t(unsigned long, info.argsz, sizeof(info)); mutex_lock(&iommu->lock); info.flags = VFIO_IOMMU_INFO_PGSIZES;