From: Jason Baron <jbaron@akamai.com>
To: linux@roeck-us.net, jdelvare@suse.com
Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] hwmon: (nct7904) Correct divide by 0
Date: Fri, 21 Aug 2020 12:20:14 -0400 [thread overview]
Message-ID: <1598026814-2604-1-git-send-email-jbaron@akamai.com> (raw)
We hit a kernel panic due to a divide by 0 in nct7904_read_fan() for
the hwmon_fan_min case. Extend the check to hwmon_fan_input case as well
for safety.
[ 1656.545650] divide error: 0000 [#1] SMP PTI
[ 1656.545779] CPU: 12 PID: 18010 Comm: sensors Not tainted 5.4.47 #1
[ 1656.546065] RIP: 0010:nct7904_read+0x1e9/0x510 [nct7904]
...
[ 1656.546549] RAX: 0000000000149970 RBX: ffffbd6b86bcbe08 RCX: 0000000000000000
...
[ 1656.547548] Call Trace:
[ 1656.547665] hwmon_attr_show+0x32/0xd0 [hwmon]
[ 1656.547783] dev_attr_show+0x18/0x50
[ 1656.547898] sysfs_kf_seq_show+0x99/0x120
[ 1656.548013] seq_read+0xd8/0x3e0
[ 1656.548127] vfs_read+0x89/0x130
[ 1656.548234] ksys_read+0x7d/0xb0
[ 1656.548342] do_syscall_64+0x48/0x110
[ 1656.548451] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
drivers/hwmon/nct7904.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/nct7904.c b/drivers/hwmon/nct7904.c
index b042569..242ff8b 100644
--- a/drivers/hwmon/nct7904.c
+++ b/drivers/hwmon/nct7904.c
@@ -231,7 +231,7 @@ static int nct7904_read_fan(struct device *dev, u32 attr, int channel,
if (ret < 0)
return ret;
cnt = ((ret & 0xff00) >> 3) | (ret & 0x1f);
- if (cnt == 0x1fff)
+ if (cnt == 0 || cnt == 0x1fff)
rpm = 0;
else
rpm = 1350000 / cnt;
@@ -243,7 +243,7 @@ static int nct7904_read_fan(struct device *dev, u32 attr, int channel,
if (ret < 0)
return ret;
cnt = ((ret & 0xff00) >> 3) | (ret & 0x1f);
- if (cnt == 0x1fff)
+ if (cnt == 0 || cnt == 0x1fff)
rpm = 0;
else
rpm = 1350000 / cnt;
--
2.7.4
next reply other threads:[~2020-08-21 16:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 16:20 Jason Baron [this message]
2020-08-21 18:27 ` Guenter Roeck
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=1598026814-2604-1-git-send-email-jbaron@akamai.com \
--to=jbaron@akamai.com \
--cc=jdelvare@suse.com \
--cc=linux-hwmon@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@roeck-us.net \
/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
all inboxes | Powered by JetHome®