From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44C56C43217 for ; Sat, 19 Nov 2022 02:11:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230361AbiKSCLi (ORCPT ); Fri, 18 Nov 2022 21:11:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229542AbiKSCLe (ORCPT ); Fri, 18 Nov 2022 21:11:34 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 401DC2B602; Fri, 18 Nov 2022 18:11:32 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D3AEAB82670; Sat, 19 Nov 2022 02:11:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61E75C433D6; Sat, 19 Nov 2022 02:11:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668823889; bh=FV9cKpXU40ig1PLuoNySucKUItQdqkjAvnyrw0XqHSw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Xqui0203d2tMKEa1PDdyAfLPl0SCHcC3AFot9Jl+N2uLcfWT2dIzgbsd76YxhQtPR uThKRP+/orGcYphMJkShjd77oiCljvujhacH851JR6qvzi1oFMjJ1eTe/ak2fa4kmX 74Nk3OLqCcczYyEgiopedJ6SLfh3QrDQbSXF0Y3KHkMpEZWvfso/pF6FPI5f9Y7TIA 4CzVKk38NKrB9b8AwAqHSaDg1OXYPKrNOSzZl3onR3uygZkakxL21aM1Ubx2KHdjk7 7euS4AUUhWC08l4UqR9CoR++d3sy77UPXIyvUUsPvVPX3v7+nzRpqk6rG+7myG2Ov2 AWq+wfo9Lufxg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Paul Zhang , Johannes Berg , Sasha Levin , johannes@sipsolutions.net, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 6.0 02/44] wifi: cfg80211: Fix bitrates overflow issue Date: Fri, 18 Nov 2022 21:10:42 -0500 Message-Id: <20221119021124.1773699-2-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221119021124.1773699-1-sashal@kernel.org> References: <20221119021124.1773699-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul Zhang [ Upstream commit 18429c51c7ff6e6bfd627316c54670230967a7e5 ] When invoking function cfg80211_calculate_bitrate_eht about (320 MHz, EHT-MCS 13, EHT-NSS 2, EHT-GI 0), which means the parameters as flags: 0x80, bw: 7, mcs: 13, eht_gi: 0, nss: 2, this formula (result * rate->nss) will overflow and causes the returned bitrate to be 3959 when it should be 57646. Here is the explanation: u64 tmp; u32 result; … /* tmp = result = 4 * rates_996[0] * = 4 * 480388888 = 0x72889c60 */ tmp = result; /* tmp = 0x72889c60 * 6144 = 0xabccea90000 */ tmp *= SCALE; /* tmp = 0xabccea90000 / mcs_divisors[13] * = 0xabccea90000 / 5120 = 0x8970bba6 */ do_div(tmp, mcs_divisors[rate->mcs]); /* result = 0x8970bba6 */ result = tmp; /* normally (result * rate->nss) = 0x8970bba6 * 2 = 0x112e1774c, * but since result is u32, (result * rate->nss) = 0x12e1774c, * overflow happens and it loses the highest bit. * Then result = 0x12e1774c / 8 = 39595753, */ result = (result * rate->nss) / 8; Signed-off-by: Paul Zhang Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- net/wireless/util.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/wireless/util.c b/net/wireless/util.c index 775836f6785a..450d609b512a 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -1555,10 +1555,12 @@ static u32 cfg80211_calculate_bitrate_eht(struct rate_info *rate) tmp = result; tmp *= SCALE; do_div(tmp, mcs_divisors[rate->mcs]); - result = tmp; /* and take NSS */ - result = (result * rate->nss) / 8; + tmp *= rate->nss; + do_div(tmp, 8); + + result = tmp; return result / 10000; } -- 2.35.1