From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933841AbeCMQYP (ORCPT ); Tue, 13 Mar 2018 12:24:15 -0400 Received: from gateway24.websitewelcome.com ([192.185.51.35]:33902 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932695AbeCMQYN (ORCPT ); Tue, 13 Mar 2018 12:24:13 -0400 Date: Tue, 13 Mar 2018 11:24:11 -0500 From: "Gustavo A. R. Silva" To: David Laight , Ben Skeggs , David Airlie Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH v2] drm/nouveau/secboot: remove VLA usage Message-ID: <20180313162411.GA1983@embeddedgus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.175.117.58 X-Source-L: No X-Exim-ID: 1evmii-002mF9-4E X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedgus) [189.175.117.58]:57352 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 12 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In preparation to enabling -Wvla, remove VLA. In this particular case directly use macro NVKM_MSGQUEUE_CMDLINE_SIZE instead of local variable cmdline_size. Also, remove cmdline_size as it is not actually useful anymore. The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug. Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Gustavo A. R. Silva --- Changes in v2: - Use sizeof(buf) instead of NVKM_MSGQUEUE_CMDLINE_SIZE. This change is based on the feedback provided by David Laight. Thanks David. drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c b/drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c index 6f10b09..1e1f1c6 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c @@ -80,12 +80,11 @@ acr_ls_msgqueue_post_run(struct nvkm_msgqueue *queue, struct nvkm_falcon *falcon, u32 addr_args) { struct nvkm_device *device = falcon->owner->device; - u32 cmdline_size = NVKM_MSGQUEUE_CMDLINE_SIZE; - u8 buf[cmdline_size]; + u8 buf[NVKM_MSGQUEUE_CMDLINE_SIZE]; - memset(buf, 0, cmdline_size); + memset(buf, 0, sizeof(buf)); nvkm_msgqueue_write_cmdline(queue, buf); - nvkm_falcon_load_dmem(falcon, buf, addr_args, cmdline_size, 0); + nvkm_falcon_load_dmem(falcon, buf, addr_args, sizeof(buf), 0); /* rearm the queue so it will wait for the init message */ nvkm_msgqueue_reinit(queue); -- 2.7.4