From patchwork Mon Aug 23 17:21:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 501717 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-21.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C231BC432BE for ; Mon, 23 Aug 2021 17:18:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAE8461528 for ; Mon, 23 Aug 2021 17:18:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230527AbhHWRTe (ORCPT ); Mon, 23 Aug 2021 13:19:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:50414 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229755AbhHWRTe (ORCPT ); Mon, 23 Aug 2021 13:19:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A6ED961501; Mon, 23 Aug 2021 17:18:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629739131; bh=sXFez6GCJcIUZP7DNnqylGtMEnOm11ZhHcPII95H6rg=; h=Date:From:To:Cc:Subject:From; b=KcM68az9xJ3QqQDGOGi8XcXdovAC7wHrbTtBKPeji1izXq1+0xpCvg8MZ231KbKYK XQ3E1fbYdVsTlL+Hd1leFAKj2lo90mgEbk0UT3Wb2indGHOlcIKJ6fA+SWQAoVNO0e 9T2kve/00ustILUHoVFMozWEMSRKw26OSnxWuULf1qnJBUxze1bmWnRVnUT+RGJlt3 MPETqjS3NbwMKnXhDVy52QbpHJ00mJmlJzzZhOoxRxxRcDMtepK1xPWSaw71v73u7X s0MCLiyjHGqel7QpDxZQYCFfNj7q8WWg72hNkZinheYS3ktpv7iTAnYe7OGiRvfvlh x40hX50jvUd0A== Date: Mon, 23 Aug 2021 12:21:59 -0500 From: "Gustavo A. R. Silva" To: Kalle Valo , "David S. Miller" , Jakub Kicinski Cc: ath11k@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH][next] ath11k: Replace one-element array with flexible-array member Message-ID: <20210823172159.GA25800@embeddedor> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use "flexible array members"[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. Refactor the code a bit according to the use of a flexible-array member in struct scan_chan_list_params instead of a one-element array, and use the struct_size() helper. Also, save 25 (too many) bytes that were being allocated: $ pahole -C channel_param drivers/net/wireless/ath/ath11k/reg.o struct channel_param { u8 chan_id; /* 0 1 */ u8 pwr; /* 1 1 */ u32 mhz; /* 2 4 */ /* Bitfield combined with next fields */ u32 half_rate:1; /* 4:16 4 */ u32 quarter_rate:1; /* 4:17 4 */ u32 dfs_set:1; /* 4:18 4 */ u32 dfs_set_cfreq2:1; /* 4:19 4 */ u32 is_chan_passive:1; /* 4:20 4 */ u32 allow_ht:1; /* 4:21 4 */ u32 allow_vht:1; /* 4:22 4 */ u32 allow_he:1; /* 4:23 4 */ u32 set_agile:1; /* 4:24 4 */ u32 psc_channel:1; /* 4:25 4 */ /* XXX 6 bits hole, try to pack */ u32 phy_mode; /* 8 4 */ u32 cfreq1; /* 12 4 */ u32 cfreq2; /* 16 4 */ char maxpower; /* 20 1 */ char minpower; /* 21 1 */ char maxregpower; /* 22 1 */ u8 antennamax; /* 23 1 */ u8 reg_class_id; /* 24 1 */ /* size: 25, cachelines: 1, members: 21 */ /* sum members: 23 */ /* sum bitfield members: 10 bits, bit holes: 1, sum bit holes: 6 bits */ /* last cacheline: 25 bytes */ } __attribute__((__packed__)); as previously, sizeof(struct scan_chan_list_params) was 32 bytes: $ pahole -C scan_chan_list_params drivers/net/wireless/ath/ath11k/reg.o struct scan_chan_list_params { u32 pdev_id; /* 0 4 */ u16 nallchans; /* 4 2 */ struct channel_param ch_param[1]; /* 6 25 */ /* size: 32, cachelines: 1, members: 3 */ /* padding: 1 */ /* last cacheline: 32 bytes */ }; and now with the flexible array transformation it is just 8 bytes: $ pahole -C scan_chan_list_params drivers/net/wireless/ath/ath11k/reg.o struct scan_chan_list_params { u32 pdev_id; /* 0 4 */ u16 nallchans; /* 4 2 */ struct channel_param ch_param[]; /* 6 0 */ /* size: 8, cachelines: 1, members: 3 */ /* padding: 2 */ /* last cacheline: 8 bytes */ }; This helps with the ongoing efforts to globally enable -Warray-bounds and get us closer to being able to tighten the FORTIFY_SOURCE routines on memcpy(). This issue was found with the help of Coccinelle and audited and fixed, manually. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/109 Signed-off-by: Gustavo A. R. Silva --- drivers/net/wireless/ath/ath11k/reg.c | 7 ++----- drivers/net/wireless/ath/ath11k/wmi.c | 2 +- drivers/net/wireless/ath/ath11k/wmi.h | 2 +- 3 files changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/ath/ath11k/reg.c b/drivers/net/wireless/ath/ath11k/reg.c index e1a1df169034..c83d265185f1 100644 --- a/drivers/net/wireless/ath/ath11k/reg.c +++ b/drivers/net/wireless/ath/ath11k/reg.c @@ -97,7 +97,6 @@ int ath11k_reg_update_chan_list(struct ath11k *ar) struct channel_param *ch; enum nl80211_band band; int num_channels = 0; - int params_len; int i, ret; bands = hw->wiphy->bands; @@ -117,10 +116,8 @@ int ath11k_reg_update_chan_list(struct ath11k *ar) if (WARN_ON(!num_channels)) return -EINVAL; - params_len = sizeof(struct scan_chan_list_params) + - num_channels * sizeof(struct channel_param); - params = kzalloc(params_len, GFP_KERNEL); - + params = kzalloc(struct_size(params, ch_param, num_channels), + GFP_KERNEL); if (!params) return -ENOMEM; diff --git a/drivers/net/wireless/ath/ath11k/wmi.c b/drivers/net/wireless/ath/ath11k/wmi.c index 6c253eae9d06..0a634ba04509 100644 --- a/drivers/net/wireless/ath/ath11k/wmi.c +++ b/drivers/net/wireless/ath/ath11k/wmi.c @@ -2285,7 +2285,7 @@ int ath11k_wmi_send_scan_chan_list_cmd(struct ath11k *ar, u16 num_send_chans, num_sends = 0, max_chan_limit = 0; u32 *reg1, *reg2; - tchan_info = &chan_list->ch_param[0]; + tchan_info = chan_list->ch_param; while (chan_list->nallchans) { len = sizeof(*cmd) + TLV_HDR_SIZE; max_chan_limit = (wmi->wmi_ab->max_msg_len[ar->pdev_idx] - len) / diff --git a/drivers/net/wireless/ath/ath11k/wmi.h b/drivers/net/wireless/ath/ath11k/wmi.h index d35c47e0b19d..d9c83726f65d 100644 --- a/drivers/net/wireless/ath/ath11k/wmi.h +++ b/drivers/net/wireless/ath/ath11k/wmi.h @@ -3608,7 +3608,7 @@ struct wmi_stop_scan_cmd { struct scan_chan_list_params { u32 pdev_id; u16 nallchans; - struct channel_param ch_param[1]; + struct channel_param ch_param[]; }; struct wmi_scan_chan_list_cmd {