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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 0EC05C352A3 for ; Mon, 10 Feb 2020 14:26:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D904B2082F for ; Mon, 10 Feb 2020 14:26:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728281AbgBJO0v (ORCPT ); Mon, 10 Feb 2020 09:26:51 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:40670 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727429AbgBJO0u (ORCPT ); Mon, 10 Feb 2020 09:26:50 -0500 Received: from 1.general.cking.uk.vpn ([10.172.193.212] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1j1A1P-0008CF-1L; Mon, 10 Feb 2020 14:26:47 +0000 From: Colin King To: Antti Palosaari , Mauro Carvalho Chehab , linux-media@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] media: tda10071: fix unsigned sign extension overflow Date: Mon, 10 Feb 2020 14:26:46 +0000 Message-Id: <20200210142646.431957-1-colin.king@canonical.com> X-Mailer: git-send-email 2.25.0 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Colin Ian King The shifting of buf[3] by 24 bits to the left will be promoted to a 32 bit signed int and then sign-extended to an unsigned long. In the unlikely event that the the top bit of buf[3] is set then all then all the upper bits end up as also being set because of the sign-extension and this affect the ev->post_bit_error sum. Fix this by using the temporary u32 variable bit_error to avoid the sign-extension promotion. This also removes the need to do the computation twice. Addresses-Coverity: ("Unintended sign extension") Fixes: 267897a4708f ("[media] tda10071: implement DVBv5 statistics") Signed-off-by: Colin Ian King --- drivers/media/dvb-frontends/tda10071.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/media/dvb-frontends/tda10071.c b/drivers/media/dvb-frontends/tda10071.c index 1953b00b3e48..685c0ac71819 100644 --- a/drivers/media/dvb-frontends/tda10071.c +++ b/drivers/media/dvb-frontends/tda10071.c @@ -470,10 +470,11 @@ static int tda10071_read_status(struct dvb_frontend *fe, enum fe_status *status) goto error; if (dev->delivery_system == SYS_DVBS) { - dev->dvbv3_ber = buf[0] << 24 | buf[1] << 16 | - buf[2] << 8 | buf[3] << 0; - dev->post_bit_error += buf[0] << 24 | buf[1] << 16 | - buf[2] << 8 | buf[3] << 0; + u32 bit_error = buf[0] << 24 | buf[1] << 16 | + buf[2] << 8 | buf[3] << 0; + + dev->dvbv3_ber = bit_error; + dev->post_bit_error += bit_error; c->post_bit_error.stat[0].scale = FE_SCALE_COUNTER; c->post_bit_error.stat[0].uvalue = dev->post_bit_error; dev->block_error += buf[4] << 8 | buf[5] << 0; -- 2.25.0