From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Date: Sat, 30 Sep 2017 20:14:46 +0000 Subject: Re: [PATCH] staging: iio: ade7759: fix signed extension bug on shift of a u8 Message-Id: <20170930211446.07222690@archlinux> List-Id: References: <20170913170202.8029-1-colin.king@canonical.com> In-Reply-To: <20170913170202.8029-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Colin King Cc: Lars-Peter Clausen , Michael Hennerich , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, 13 Sep 2017 18:02:02 +0100 Colin King wrote: > 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 Applied to the fixes-togreg branch of iio.git. Thanks, Jonathan > --- > 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: