[PATCH] 2.5.24 matroxfb memory corruption

  When James converted all drivers to unified do_install_cmap(), he
blindly changed also matroxfb, which happily uses fbcon.currcon == -1.
This caused memory corruption because of memory before fb_display[]
array was overwritten.

  Default do_install_cmap() also installed invalid default color map in
some matroxfb resolutions.  Not all world have >= 4bpp.

drivers/video/matrox/matroxfb_base.c

@@ -141,6 +141,19 @@ static struct fb_var_screeninfo vesafb_defined = {
 
 
 /* --------------------------------------------------------------------- */
+static inline void my_install_cmap(WPMINFO2)
+{
+	/* Do not touch this code if you do not understand what it does! */
+	/* Never try to use do_install_cmap() instead. It is crap. */
+	struct fb_cmap* cmap = &ACCESS_FBINFO(currcon_display)->cmap;
+
+	if (cmap->len)
+		fb_set_cmap(cmap, 1, &ACCESS_FBINFO(fbcon));
+	else
+		fb_set_cmap(fb_default_cmap(ACCESS_FBINFO(curr.cmap_len)),
+			    1, &ACCESS_FBINFO(fbcon));
+}
+
 
 static void matrox_pan_var(WPMINFO struct fb_var_screeninfo *var) {
 	unsigned int pos;
@@ -869,7 +882,7 @@ static int matroxfb_set_var(struct fb_var_screeninfo *var, int con,
 				up_read(&ACCESS_FBINFO(altout.lock));
 			}
 			matrox_cfbX_init(PMINFO display);
-			do_install_cmap(ACCESS_FBINFO(fbcon.currcon),&ACCESS_FBINFO(fbcon));
+			my_install_cmap(PMINFO2);
 #if defined(CONFIG_FB_COMPAT_XPMAC)
 			if (console_fb_info == &ACCESS_FBINFO(fbcon)) {
 				int vmode, cmode;

drivers/video/matrox/matroxfb_crtc2.c

@@ -84,6 +84,19 @@ static int matroxfb_dh_setcolreg(unsigned regno, unsigned red, unsigned green,
 #undef m2info
 }
 
+static inline void my_install_cmap(struct matroxfb_dh_fb_info* m2info)
+{
+	/* Do not touch this code if you do not understand what it does! */
+	/* Never try to use do_install_cmap() instead. It is crap. */
+	struct fb_cmap* cmap = &m2info->currcon_display->cmap;
+	
+	if (cmap->len)
+		fb_set_cmap(cmap, 1, &m2info->fbcon);
+	else
+		fb_set_cmap(fb_default_cmap(16), 1, &m2info->fbcon);
+}
+
+
 static void matroxfb_dh_restore(struct matroxfb_dh_fb_info* m2info,
 		struct my_timming* mt,
 		struct display* p,
@@ -439,7 +452,7 @@ static int matroxfb_dh_set_var(struct fb_var_screeninfo* var, int con,
 			up_read(&ACCESS_FBINFO(altout.lock));
 		}
 		matroxfb_dh_cfbX_init(m2info, p);
-		do_install_cmap(ACCESS_FBINFO(fbcon.currcon), &ACCESS_FBINFO(fbcon));
+		my_install_cmap(m2info);
 	}
 	return 0;
 #undef m2info