From d0716dde375eb6bff332763bb2137302120d263d Mon Sep 17 00:00:00 2001 From: Sien Wu Date: Thu, 1 Sep 2016 18:24:29 -0500 Subject: [PATCH] spi: Prevent unexpected SPI time out due to arithmetic overflow 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 Signed-off-by: Mark Brown --- drivers/spi/spi.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51ad42fad567..ac889df9b1f3 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)); } -- 2.20.1