From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: [PATCH v2] drm/nouveau/secboot: remove VLA usage Date: Tue, 13 Mar 2018 11:24:11 -0500 Message-ID: <20180313162411.GA1983@embeddedgus> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org 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" List-Id: nouveau.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