From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752804AbcIAXzZ (ORCPT ); Thu, 1 Sep 2016 19:55:25 -0400 Received: from skprod3.natinst.com ([130.164.80.24]:50821 "EHLO ni.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750859AbcIAXzU (ORCPT ); Thu, 1 Sep 2016 19:55:20 -0400 X-Greylist: delayed 1836 seconds by postgrey-1.27 at vger.kernel.org; Thu, 01 Sep 2016 19:55:20 EDT From: Sien Wu To: broonie@kernel.org Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Sien Wu Subject: [RFC v2] spi: Prevent unexpected SPI time out due to arithmetic overflow Date: Thu, 1 Sep 2016 18:24:29 -0500 Message-Id: <1472772269-44752-1-git-send-email-sien.wu@ni.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <20160901195747.GN5967> References: <20160901195747.GN5967> X-MIMETrack: Itemize by SMTP Server on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 09/01/2016 06:24:42 PM, Serialize by Router on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 09/01/2016 06:24:42 PM, Serialize complete at 09/01/2016 06:24:42 PM X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-09-01_09:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When reading SPI flash as MTD device, the transfer length is directly passed to the spi driver. If the requested data size exceeds 512KB, it will cause the time out calculation to overflow since transfer length is 32-bit unsigned integer. This issue is resolved by using 64-bit unsigned integer to perform the arithmetic. Signed-off-by: Sien Wu Acked-by: Brad Keryan Acked-by: Gratian Crisan Acked-by: Brad Mouring Natinst-ReviewBoard-ID 150232 --- Updated the patch to apply to latest spi.c --- drivers/spi/spi.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51ad42f..ac889df 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -960,7 +960,7 @@ static int spi_transfer_one_message(struct spi_master *master, struct spi_transfer *xfer; bool keep_cs = false; int ret = 0; - unsigned long ms = 1; + unsigned long long ms = 1; struct spi_statistics *statm = &master->statistics; struct spi_statistics *stats = &msg->spi->statistics; @@ -991,9 +991,13 @@ static int spi_transfer_one_message(struct spi_master *master, if (ret > 0) { ret = 0; - ms = xfer->len * 8 * 1000 / xfer->speed_hz; + ms = 8LL * 1000LL * xfer->len; + do_div(ms, xfer->speed_hz); ms += ms + 100; /* some tolerance */ + if (ms > UINT_MAX) + ms = UINT_MAX; + ms = wait_for_completion_timeout(&master->xfer_completion, msecs_to_jiffies(ms)); } -- 1.7.1