From patchwork Wed Jan 6 06:16:25 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Prasad Pandit X-Patchwork-Id: 563706 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id C0B2F1402DE for ; Wed, 6 Jan 2016 17:17:02 +1100 (AEDT) Received: from localhost ([::1]:52801 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGhP2-0006wE-GR for incoming@patchwork.ozlabs.org; Wed, 06 Jan 2016 01:17:00 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50348) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGhOn-0006ee-9Z for qemu-devel@nongnu.org; Wed, 06 Jan 2016 01:16:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aGhOj-0002ki-Sx for qemu-devel@nongnu.org; Wed, 06 Jan 2016 01:16:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49335) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGhOj-0002ka-NI for qemu-devel@nongnu.org; Wed, 06 Jan 2016 01:16:41 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 42E08351DEF; Wed, 6 Jan 2016 06:16:37 +0000 (UTC) Received: from javelin.localdomain (vpn-201-229.tlv.redhat.com [10.35.201.229]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u066GRGc021444 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 6 Jan 2016 01:16:31 -0500 From: P J P To: Stefan Weil Date: Wed, 6 Jan 2016 11:46:25 +0530 Message-Id: <1452060985-25843-1-git-send-email-ppandit@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Peter Maydell , Prasad J Pandit , Qemu devel , Donghai Zdh Subject: [Qemu-devel] [PATCH v2 for v2.3.0] fw_cfg: add check to validate current entry value X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Prasad J Pandit When processing firmware configurations, an OOB r/w access occurs if 's->cur_entry' is set to be invalid(FW_CFG_INVALID=0xffff). Add a check to validate 's->cur_entry' to avoid such access. Reported-by: Donghai Zdh Signed-off-by: Prasad J Pandit --- hw/nvram/fw_cfg.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) Updated as per review in -> https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg00398.html diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 68eff77..e73c0fb 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -233,12 +233,15 @@ static void fw_cfg_reboot(FWCfgState *s) static void fw_cfg_write(FWCfgState *s, uint8_t value) { int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; trace_fw_cfg_write(s, value); - if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback && - s->cur_offset < e->len) { + if (s->cur_entry & FW_CFG_WRITE_CHANNEL + && e != NULL + && e->callback + && s->cur_offset < e->len) { e->data[s->cur_offset++] = value; if (s->cur_offset == e->len) { e->callback(e->callback_opaque, e->data); @@ -267,7 +270,8 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key) static uint8_t fw_cfg_read(FWCfgState *s) { int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; uint8_t ret; if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >= e->len)