From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932940AbcH2ODR (ORCPT ); Mon, 29 Aug 2016 10:03:17 -0400 Received: from skprod2.natinst.com ([130.164.80.23]:34725 "EHLO ni.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932609AbcH2ODP (ORCPT ); Mon, 29 Aug 2016 10:03:15 -0400 From: Sien Wu To: broonie@kernel.org Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Sien Wu Subject: [RFC] spi: Prevent unexpected SPI time out due to arithmetic overflow Date: Mon, 29 Aug 2016 09:02:47 -0500 Message-Id: <1472479367-50682-1-git-send-email-sien.wu@ni.com> X-Mailer: git-send-email 1.7.1 X-MIMETrack: Itemize by SMTP Server on US-AUS-MGWOut1/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 08/29/2016 09:03:12 AM, Serialize by Router on US-AUS-MGWOut1/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 08/29/2016 09:03:12 AM, Serialize complete at 08/29/2016 09:03:12 AM X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-29_07:,, 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 --- drivers/spi/spi.c | 11 ++++++++--- 1 files changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 029dbd3..a186a62 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -678,7 +678,7 @@ 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; spi_set_cs(msg->spi, true); @@ -697,11 +697,16 @@ 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)); + msecs_to_jiffies(ms)); } if (ms == 0) { -- 1.7.1