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[2620:137:e000::1:20]) by mx.google.com with ESMTP id s186-20020a635ec3000000b00553851380besi149974pgb.397.2023.08.09.15.04.06; Wed, 09 Aug 2023 15:04:52 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=InSW0MVN; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229672AbjHIVE1 (ORCPT + 99 others); Wed, 9 Aug 2023 17:04:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232473AbjHIVEW (ORCPT ); Wed, 9 Aug 2023 17:04:22 -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 1F57A1BCF for ; Wed, 9 Aug 2023 14:03:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691615021; 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=InSW0MVNMNbJd8JwevIdPs3egtpKzcKEOgbj0tEXjgNbsAuAjqgKXvpS3Etq0pPZQg0d2X dm3LHS/vp7KlW+XAHemZEb31m+WUXu5l/52icG9ZcCvihBA0faMBesaPrxqLlgvA6Q2HY/ eX+dZbLn8CVpdrHNmrvrbOFdrUAfgP0= 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 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE 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: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773790762109279848 X-GMAIL-MSGID: 1773790762109279848 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 --- 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;