From patchwork Sun Feb 24 12:54:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 10827899 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 501AC1390 for ; Sun, 24 Feb 2019 12:55:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3DC7E2B589 for ; Sun, 24 Feb 2019 12:55:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 31D472B595; Sun, 24 Feb 2019 12:55:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8CDAA2B589 for ; Sun, 24 Feb 2019 12:55:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728308AbfBXMzW (ORCPT ); Sun, 24 Feb 2019 07:55:22 -0500 Received: from 212-186-180-163.static.upcbusiness.at ([212.186.180.163]:47998 "EHLO cgate.sperl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725956AbfBXMzW (ORCPT ); Sun, 24 Feb 2019 07:55:22 -0500 Received: from hc1.intern.sperl.org (account martin@sperl.org [10.10.10.59] verified) by sperl.org (CommuniGate Pro SMTP 6.2.1 _community_) with ESMTPSA id 7757563; Sun, 24 Feb 2019 12:55:07 +0000 From: kernel@martin.sperl.org To: Mark Brown , Eric Anholt , Stefan Wahren , Hubert Denkmair , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Cc: Martin Sperl Subject: [PATCH 7/9] spi: bcm2835aux: remove dangerous uncontrolled read of fifo Date: Sun, 24 Feb 2019 12:54:38 +0000 Message-Id: <20190224125440.16117-8-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190224125440.16117-1-kernel@martin.sperl.org> References: <20190224125440.16117-1-kernel@martin.sperl.org> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Martin Sperl This read of the fifo is a potential candidate for a race condition as the spi transfer is not necessarily finished and so can lead to an early read of the fifo that still misses data. So it has been removed - an additional loop will read the fifo correctly. Fixes: 1ea29b39f4c812ece2f936065a0a3d6fe44a263e (Note: requires Patch 6) Suggested-by: Hubert Denkmair Signed-off-by: Martin Sperl --- drivers/spi/spi-bcm2835aux.c | 7 ------- 1 file changed, 7 deletions(-) -- 2.11.0 diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index 9552f5343982..8821fc183ca0 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -246,13 +246,6 @@ static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs) BCM2835_AUX_SPI_STAT_TX_FULL))) { bcm2835aux_wr_fifo(bs); } - - /* and check if we have reached "done" */ - while (bs->rx_len && - (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) & - BCM2835_AUX_SPI_STAT_BUSY))) { - bcm2835aux_rd_fifo(bs); - } } static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)