From: Colin King <colin.king@canonical.com>
To: Antti Palosaari <crope@iki.fi>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] media: tda10071: fix unsigned sign extension overflow
Date: Mon, 10 Feb 2020 14:26:46 +0000 [thread overview]
Message-ID: <20200210142646.431957-1-colin.king@canonical.com> (raw)
From: Colin Ian King <colin.king@canonical.com>
The shifting of buf[3] by 24 bits to the left will be promoted to
a 32 bit signed int and then sign-extended to an unsigned long. In
the unlikely event that the the top bit of buf[3] is set then all
then all the upper bits end up as also being set because of
the sign-extension and this affect the ev->post_bit_error sum.
Fix this by using the temporary u32 variable bit_error to avoid
the sign-extension promotion. This also removes the need to do the
computation twice.
Addresses-Coverity: ("Unintended sign extension")
Fixes: 267897a4708f ("[media] tda10071: implement DVBv5 statistics")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
drivers/media/dvb-frontends/tda10071.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/media/dvb-frontends/tda10071.c b/drivers/media/dvb-frontends/tda10071.c
index 1953b00b3e48..685c0ac71819 100644
--- a/drivers/media/dvb-frontends/tda10071.c
+++ b/drivers/media/dvb-frontends/tda10071.c
@@ -470,10 +470,11 @@ static int tda10071_read_status(struct dvb_frontend *fe, enum fe_status *status)
goto error;
if (dev->delivery_system == SYS_DVBS) {
- dev->dvbv3_ber = buf[0] << 24 | buf[1] << 16 |
- buf[2] << 8 | buf[3] << 0;
- dev->post_bit_error += buf[0] << 24 | buf[1] << 16 |
- buf[2] << 8 | buf[3] << 0;
+ u32 bit_error = buf[0] << 24 | buf[1] << 16 |
+ buf[2] << 8 | buf[3] << 0;
+
+ dev->dvbv3_ber = bit_error;
+ dev->post_bit_error += bit_error;
c->post_bit_error.stat[0].scale = FE_SCALE_COUNTER;
c->post_bit_error.stat[0].uvalue = dev->post_bit_error;
dev->block_error += buf[4] << 8 | buf[5] << 0;
--
2.25.0
next reply other threads:[~2020-02-10 14:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 14:26 Colin King [this message]
2020-02-10 14:41 ` [PATCH] media: tda10071: fix unsigned sign extension overflow Dan Carpenter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200210142646.431957-1-colin.king@canonical.com \
--to=colin.king@canonical.com \
--cc=crope@iki.fi \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).