linux-kernel - [PATCH 3.2 34/94] staging: iio: ade7759: fix signed extension bug on shift of a u8

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 28 Dec 2017 16:59:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Colin Ian King" <colin.king@...onical.com>,
        "Jonathan Cameron" <Jonathan.Cameron@...wei.com>
Subject: [PATCH 3.2 34/94] staging: iio: ade7759: fix signed extension bug
 on shift of a u8

3.2.97-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Colin Ian King <colin.king@...onical.com>

commit 13ffe9a26df4e156363579b25c904dd0b1e31bfb upstream.

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 <colin.king@...onical.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/staging/iio/meter/ade7759.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/iio/meter/ade7759.c
+++ b/drivers/staging/iio/meter/ade7759.c
@@ -128,7 +128,7 @@ static int ade7759_spi_read_reg_40(struc
 				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: