[PATCH] therm.c: Adding an array index check before accessing an element.

[Andrey Shumilin]

It is possible to access an element at index -1 if at the
first iteration of the loop the result of switch is equal to 0x25
Added variable checking.

Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Andrey Shumilin <shum.sdl at nppct.ru>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/therm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/therm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/therm.c
index 5babc5a7c7d5..78387053f214 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/therm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/therm.c
@@ -180,6 +180,8 @@ nvbios_therm_fan_parse(struct nvkm_bios *bios, struct nvbios_therm_fan *fan)
 			cur_trip->fan_duty = duty_lut[(value & 0xf000) >> 12];
 			break;
 		case 0x25:
+			if (fan->nr_fan_trip == 0)
+				fan->nr_fan_trip++;
 			cur_trip = &fan->trip[fan->nr_fan_trip - 1];
 			cur_trip->fan_duty = value;
 			break;
-- 
2.30.2