From 9054d58440927f08efa71c3da211acbdd18e634a Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Fri, 21 Aug 2020 12:20:14 -0400 Subject: [PATCH] hwmon: (nct7904) Correct divide by 0 [ Upstream commit 8aebbbb2d573d0b4afc08b90ac7d73dba2d9da97 ] 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 Fixes: d65a5102a99f5 ("hwmon: (nct7904) Convert to use new hwmon registration API") Signed-off-by: Jason Baron Link: https://lore.kernel.org/r/1598026814-2604-1-git-send-email-jbaron@akamai.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- 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 dfb122b5e1b7..b812b199e5e5 100644 --- a/drivers/hwmon/nct7904.c +++ b/drivers/hwmon/nct7904.c @@ -197,7 +197,7 @@ 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; @@ -209,7 +209,7 @@ 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;