thermal: intel: x86_pkg_temp_thermal: Add lower bound check for sysfs input

When setting a trip point temperature from sysfs, there is an upper
bound check on the user input, but no lower bound check.

As hardware register has 7 bits for a trip point temperature, the offset
to tj_max of the input temperature must be equal to/less than 0x7f.
Or else,
 1. bogus temperature is updated into the trip temperature bits.
 2. the upper bits of the register can be polluted.

For example,
$ rdmsr 0x1b2
2000003
$ echo -180000 > /sys/class/thermal/thermal_zone1/trip_point_1_temp
$ rdmsr 0x1b2
3980003

Not only the trip point temp is set to 76C on this platform (tj_max is
100), the Power Notification (Bit 24) is also enabled erronously.

Fix the problem by adding lower bound check for sysfs input.

Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/all/add7a378-4d50-4ba1-81d3-a0c17db25a0b@kili.mountain/
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions