From 5e25f7b09977002b069946e82055f26e0f4aec8d Mon Sep 17 00:00:00 2001
From: Toomas Soome <tsoome@FreeBSD.org>
Date: Mon, 12 May 2025 02:07:15 +0300
Subject: [PATCH] loader: loader can pick too large font

While calculating font size based on EDID data, we can end up
selecting too large font and too small terminal. Add check to
prevent it.

Tested by:	bz, ziaee
Reviewed by:	adrian
Differential Revision:	https://reviews.freebsd.org/D50258
---
 stand/common/gfx_fb.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/stand/common/gfx_fb.c b/stand/common/gfx_fb.c
index efb210dff21..ad38a657e23 100644
--- a/stand/common/gfx_fb.c
+++ b/stand/common/gfx_fb.c
@@ -2054,7 +2054,8 @@ gfx_get_ppi(void)
  * not smaller than calculated size value.
  */
 static vt_font_bitmap_data_t *
-gfx_get_font(void)
+gfx_get_font(teken_unit_t rows, teken_unit_t cols, teken_unit_t height,
+    teken_unit_t width)
 {
 	unsigned ppi, size;
 	vt_font_bitmap_data_t *font = NULL;
@@ -2077,6 +2078,14 @@ gfx_get_font(void)
 	size = roundup(size * 2, 10) / 10;
 
 	STAILQ_FOREACH(fl, &fonts, font_next) {
+		/*
+		 * Skip too large fonts.
+		 */
+		font = fl->font_data;
+		if (height / font->vfbd_height < rows &&
+		    width / font->vfbd_width < cols)
+			continue;
+
 		next = STAILQ_NEXT(fl, font_next);
 
 		/*
@@ -2084,7 +2093,6 @@ gfx_get_font(void)
 		 * we have our font. Make sure, it actually is loaded.
 		 */
 		if (next == NULL || next->font_data->vfbd_height < size) {
-			font = fl->font_data;
 			if (font->vfbd_font == NULL ||
 			    fl->font_flags == FONT_RELOAD) {
 				if (fl->font_load != NULL &&
@@ -2093,6 +2101,7 @@ gfx_get_font(void)
 			}
 			break;
 		}
+		font = NULL;
 	}
 
 	return (font);
@@ -2123,7 +2132,7 @@ set_font(teken_unit_t *rows, teken_unit_t *cols, teken_unit_t h, teken_unit_t w)
 	}
 
 	if (font == NULL)
-		font = gfx_get_font();
+		font = gfx_get_font(*rows, *cols, h, w);
 
 	if (font != NULL) {
 		*rows = height / font->vfbd_height;