From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 423DB606A33E for ; Wed, 11 Nov 2026 15:08:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Ml/mcy8Y Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xR9vI-0007Tl-FB; Wed, 11 Nov 2026 10:07:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xR9uu-0007LG-6U for qemu-devel@nongnu.org; Wed, 11 Nov 2026 10:07:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xR9uq-0000t3-BE for qemu-devel@nongnu.org; Wed, 11 Nov 2026 10:07:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1794409625; 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; bh=UFrM4WpSySpasTj+U73aZBoiXT47gy/wAfaPfKr5U48=; b=Ml/mcy8YUmLuzLtNpYrkqK1a0RSWpDMOzfqpsYE72mwd5yzROW/Vk91MDLpo4XKZ9alZp1 r0WBVhmLBNtNMkWv9gy8W9VFHHImT9H2pJawYZ4ujsh/Rpdqd0HuTbPEBfWr7hwf+7qFgg fdSfLcluUhOWvdW7tT7/OK3UDQDZx8w= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-596-4FcVdOIrNYq1Y-kkfgNXWg-1; Wed, 11 Nov 2026 10:07:03 -0500 X-MC-Unique: 4FcVdOIrNYq1Y-kkfgNXWg-1 X-Mimecast-MFC-AGG-ID: 4FcVdOIrNYq1Y-kkfgNXWg_1794409622 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9BE4F195398E; Wed, 11 Nov 2026 15:07:02 +0000 (UTC) Received: from thuth-p1g4.redhat.com (unknown [10.44.32.37]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BBF71195608B; Wed, 11 Nov 2026 15:07:00 +0000 (UTC) From: Thomas Huth To: Kevin Wolf , qemu-devel@nongnu.org Cc: Hanna Reitz , qemu-block@nongnu.org Subject: [PATCH] block/vhdx-log: Improve sanity checks to avoid OOB accesses with bad images Date: Wed, 11 Nov 2026 16:06:59 +0100 Message-ID: <20261111150659.253918-1-thuth@redhat.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-20.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The multiplication "hdr->descriptor_count * sizeof(VHDXLogDescriptor)" in vhdx_log_hdr_is_valid() can overflow on 32-bit systems, so this function could mark bad images as valid when the truncated result is smaller than hdr->entry_length. Switch to a division on the right hand side instead to avoid the overflow problems. The second problem is in vhdx_log_read_desc(): desc_sectors is a 32-bit value, thus the multiplication "desc_sectors * VHDX_LOG_SECTOR_SIZE" is also done with 32 bit arithmetics, and the result is used as "size_t" parameter for qemu_try_blockalign(), i.e. the parameter here is also only 32 bits on 32-bit systems. Let's add a sanity check here to avoid the overflow problem that could lead to trouble later. Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3860 Signed-off-by: Thomas Huth --- block/vhdx-log.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/vhdx-log.c b/block/vhdx-log.c index 4385a2d4f62..5c20468e1e6 100644 --- a/block/vhdx-log.c +++ b/block/vhdx-log.c @@ -246,7 +246,7 @@ static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr, goto exit; } - if (hdr->descriptor_count * sizeof(VHDXLogDescriptor) > hdr->entry_length) { + if (hdr->descriptor_count > hdr->entry_length / sizeof(VHDXLogDescriptor)) { goto exit; } @@ -360,6 +360,10 @@ vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s, VHDXLogEntries *log, } desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count); + if (desc_sectors > UINT32_MAX / VHDX_LOG_SECTOR_SIZE) { + ret = -EINVAL; + goto exit; + } desc_entries = qemu_try_blockalign(bs->file->bs, desc_sectors * VHDX_LOG_SECTOR_SIZE); if (desc_entries == NULL) { -- 2.56.0