sisfb: fix pseudo_palette array size and overrun

- the pseudo_palette is only 16 elements long.
- do not write to the pseudo_palette if regno (array index) is more than 15.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/sis/sis.h

@@ -479,7 +479,7 @@ struct sis_video_info {
 	struct fb_var_screeninfo default_var;
 
 	struct fb_fix_screeninfo sisfb_fix;
-	u32		pseudo_palette[17];
+	u32		pseudo_palette[16];
 
 	struct sisfb_monitor {
 		u16 hmin;

drivers/video/sis/sis_main.c

@@ -1405,12 +1405,18 @@ sisfb_setcolreg(unsigned regno, unsigned red, unsigned green, unsigned blue,
 		}
 		break;
 	case 16:
+		if (regno >= 16)
+			break;
+
 		((u32 *)(info->pseudo_palette))[regno] =
 				(red & 0xf800)          |
 				((green & 0xfc00) >> 5) |
 				((blue & 0xf800) >> 11);
 		break;
 	case 32:
+		if (regno >= 16)
+			break;
+
 		red >>= 8;
 		green >>= 8;
 		blue >>= 8;