drm/amd/pm/powerplay/hwmgr/vega20_thermal: Prevent division by zero

commit 4e3d9508c056d7e0a56b58d5c81253e2a0d22b6c upstream.

The user can set any speed value.
If speed is greater than UINT_MAX/8, division by zero is possible.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 031db09 ("drm/amd/powerplay/vega20: enable fan RPM and pwm settings V2")
Signed-off-by: Denis Arefev <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit 80814924260cea431a8fc6137d11cc8cb331a10c)
Signed-off-by: Vijayendra Suman <[email protected]>

Author: Denis Arefev

drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega20_thermal.c

@@ -191,7 +191,7 @@ int vega20_fan_ctrl_set_fan_speed_rpm(struct pp_hwmgr *hwmgr, uint32_t speed)
 	uint32_t tach_period, crystal_clock_freq;
 	int result = 0;
 
-	if (!speed)
+	if (!speed || speed > UINT_MAX/8)
 		return -EINVAL;
 
 	if (PP_CAP(PHM_PlatformCaps_MicrocodeFanControl)) {