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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA2B7CA0EC5 for ; Mon, 11 Sep 2023 21:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240971AbjIKU4n (ORCPT ); Mon, 11 Sep 2023 16:56:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240566AbjIKOr0 (ORCPT ); Mon, 11 Sep 2023 10:47:26 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22290E40 for ; Mon, 11 Sep 2023 07:47:22 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C8F4C433C8; Mon, 11 Sep 2023 14:47:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694443641; bh=RDxYyjQekSkrs1ACZyHzxmVv59HhJS+Rbf1iu3Vkw50=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CXgwWXRgafYMhhwI6btX1PNAjfXtVLZyH6R1xZeOkGLRQzGEVkU2GUPFgiK+zjgrc s3WoRyvJv6I7g6yY77qwBge79nraqhIXTZ835XV9FmBNxdR3LIj2iDCDfR02scpTxR WEzVRGZPADC3g7VNozb2unVBODlYz8ffus0pBos0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefan Hajnoczi , Kevin Tian , Alex Williamson , Sasha Levin Subject: [PATCH 6.4 449/737] vfio/type1: fix cap_migration information leak Date: Mon, 11 Sep 2023 15:45:08 +0200 Message-ID: <20230911134703.141087751@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230911134650.286315610@linuxfoundation.org> References: <20230911134650.286315610@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stefan Hajnoczi [ Upstream commit cd24e2a60af633f157d7e59c0a6dba64f131c0b1 ] Fix an information leak where an uninitialized hole in struct vfio_iommu_type1_info_cap_migration on the stack is exposed to userspace. The definition of struct vfio_iommu_type1_info_cap_migration contains a hole as shown in this pahole(1) output: struct vfio_iommu_type1_info_cap_migration { struct vfio_info_cap_header header; /* 0 8 */ __u32 flags; /* 8 4 */ /* XXX 4 bytes hole, try to pack */ __u64 pgsize_bitmap; /* 16 8 */ __u64 max_dirty_bitmap_size; /* 24 8 */ /* size: 32, cachelines: 1, members: 4 */ /* sum members: 28, holes: 1, sum holes: 4 */ /* last cacheline: 32 bytes */ }; The cap_mig variable is filled in without initializing the hole: static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, struct vfio_info_cap *caps) { struct vfio_iommu_type1_info_cap_migration cap_mig; cap_mig.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_MIGRATION; cap_mig.header.version = 1; cap_mig.flags = 0; /* support minimum pgsize */ cap_mig.pgsize_bitmap = (size_t)1 << __ffs(iommu->pgsize_bitmap); cap_mig.max_dirty_bitmap_size = DIRTY_BITMAP_SIZE_MAX; return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig)); } The structure is then copied to a temporary location on the heap. At this point it's already too late and ioctl(VFIO_IOMMU_GET_INFO) copies it to userspace later: int vfio_info_add_capability(struct vfio_info_cap *caps, struct vfio_info_cap_header *cap, size_t size) { struct vfio_info_cap_header *header; header = vfio_info_cap_add(caps, size, cap->id, cap->version); if (IS_ERR(header)) return PTR_ERR(header); memcpy(header + 1, cap + 1, size - sizeof(*header)); return 0; } This issue was found by code inspection. Signed-off-by: Stefan Hajnoczi Reviewed-by: Kevin Tian Fixes: ad721705d09c ("vfio iommu: Add migration capability to report supported features") Link: https://lore.kernel.org/r/20230801155352.1391945-1-stefanha@redhat.com Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin --- drivers/vfio/vfio_iommu_type1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 0d2f805468e19..cd2113be632b9 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -2729,7 +2729,7 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu, static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, struct vfio_info_cap *caps) { - struct vfio_iommu_type1_info_cap_migration cap_mig; + struct vfio_iommu_type1_info_cap_migration cap_mig = {}; cap_mig.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_MIGRATION; cap_mig.header.version = 1; -- 2.40.1