fbcon: don't lose the console font across generic->chip driver switch

airlied · airlied · commit ae1287865f53 · 2013-02-07T12:37:19.000+10:00
If grub2 loads efifb/vesafb, then when systemd starts it can set the console font on that framebuffer device, however when we then load the native KMS driver, the first thing it does is tear down the generic framebuffer driver. The thing is the generic code is doing the right thing, it frees the font because otherwise it would leak memory. However we can assume that if you are removing the generic firmware driver (vesa/efi/offb), that a new driver *should* be loading soon after, so we effectively leak the font. However the old code left a dangling pointer in vc->vc_font.data and we can now reuse that dangling pointer to load the font into the new driver, now that we aren't freeing it. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=892340 Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
@@ -990,7 +990,7 @@ static const char *fbcon_startup(void)
 	}
 
 	/* Setup default font */
-	if (!p->fontdata) {
+	if (!p->fontdata && !vc->vc_font.data) {
 		if (!fontname[0] || !(font = find_font(fontname)))
 			font = get_default_font(info->var.xres,
 						info->var.yres,
@@ -1000,6 +1000,8 @@ static const char *fbcon_startup(void)
 		vc->vc_font.height = font->height;
 		vc->vc_font.data = (void *)(p->fontdata = font->data);
 		vc->vc_font.charcount = 256; /* FIXME  Need to support more fonts */
+	} else {
+		p->fontdata = vc->vc_font.data;
 	}
 
 	cols = FBCON_SWAP(ops->rotate, info->var.xres, info->var.yres);
@@ -1159,9 +1161,9 @@ static void fbcon_init(struct vc_data *vc, int init)
 	ops->p = &fb_display[fg_console];
 }
 
-static void fbcon_free_font(struct display *p)
+static void fbcon_free_font(struct display *p, bool freefont)
 {
-	if (p->userfont && p->fontdata && (--REFCOUNT(p->fontdata) == 0))
+	if (freefont && p->userfont && p->fontdata && (--REFCOUNT(p->fontdata) == 0))
 		kfree(p->fontdata - FONT_EXTRA_WORDS * sizeof(int));
 	p->fontdata = NULL;
 	p->userfont = 0;
@@ -1173,8 +1175,8 @@ static void fbcon_deinit(struct vc_data *vc)
 	struct fb_info *info;
 	struct fbcon_ops *ops;
 	int idx;
+	bool free_font = true;
 
-	fbcon_free_font(p);
 	idx = con2fb_map[vc->vc_num];
 
 	if (idx == -1)
@@ -1185,6 +1187,8 @@ static void fbcon_deinit(struct vc_data *vc)
 	if (!info)
 		goto finished;
 
+	if (info->flags & FBINFO_MISC_FIRMWARE)
+		free_font = false;
 	ops = info->fbcon_par;
 
 	if (!ops)
@@ -1196,6 +1200,8 @@ static void fbcon_deinit(struct vc_data *vc)
 	ops->flags &= ~FBCON_FLAGS_INIT;
 finished:
 
+	fbcon_free_font(p, free_font);
+
 	if (!con_is_bound(&fb_con))
 		fbcon_exit();
 
