Guenter Roeck 636dd45360 hwmon: (nct6775) Fix access to fan pulse registers
[ Upstream commit c793279c77 ]

Not all fans have a fan pulse register. This can result in reading
beyond the end of REG_FAN_PULSES and FAN_PULSE_SHIFT arrays,
and was reported by smatch as possible error.

1672          for (i = 0; i < ARRAY_SIZE(data->rpm); i++) {
                              ^^^^^^^^^^^^^^^^^^^^^^^^
			      This is a 7 element array.
...
1685                  data->fan_pulses[i] =
1686                    (nct6775_read_value(data, data->REG_FAN_PULSES[i])
1687                          >> data->FAN_PULSE_SHIFT[i]) & 0x03;
                                 ^^^^^^^^^^^^^^^^^^^^^^^^
				 FAN_PULSE_SHIFT is either 5 or 6
				 elements.

To fix the problem, we have to ensure that all REG_FAN_PULSES and
FAN_PULSE_SHIFT have the appropriate length, and that REG_FAN_PULSES
is only read if the register actually exists.

Fixes: 6c009501ff ("hwmon: (nct6775) Add support for NCT6102D/6106D")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-18 09:18:14 +02:00
2018-10-10 08:55:53 +02:00
2018-09-26 08:39:28 +02:00

Linux kernel
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

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See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.
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