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@xxxxxxxxxx> --- 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