From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Colin King To: Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , linux-iio@vger.kernel.org, devel@driverdev.osuosl.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] staging: iio: ade7759: fix signed extension bug on shift of a u8 Date: Wed, 13 Sep 2017 18:02:02 +0100 Message-Id: <20170913170202.8029-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" List-ID: From: Colin Ian King The current shift of st->rx[2] left shifts a u8 24 bits left, promotes the integer to a an int and then to a unsigned u64. If the top bit of st->rx[2] is set then we end up with all the upper bits being set to 1. Fix this by casting st->rx[2] to a u64 before the 24 bit left shift. Detected by CoverityScan CID#144940 ("Unintended sign extension") Fixes: 2919fa54ef64 ("staging: iio: meter: new driver for ADE7759 devices") Signed-off-by: Colin Ian King --- drivers/staging/iio/meter/ade7759.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c index 1691760339da..02573c517d9d 100644 --- a/drivers/staging/iio/meter/ade7759.c +++ b/drivers/staging/iio/meter/ade7759.c @@ -172,7 +172,7 @@ static int ade7759_spi_read_reg_40(struct device *dev, reg_address); goto error_ret; } - *val = ((u64)st->rx[1] << 32) | (st->rx[2] << 24) | + *val = ((u64)st->rx[1] << 32) | ((u64)st->rx[2] << 24) | (st->rx[3] << 16) | (st->rx[4] << 8) | st->rx[5]; error_ret: -- 2.14.1