On Fri, Aug 21, 2020 at 12:20:14PM -0400, Jason Baron wrote: > 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> Applied. Thanks, Guenter > --- > 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;
