PATCH] vga: split text renderer geometry cache from graphics renderer

vga_draw_text() and vga_draw_graphic() share last_width/last_height
but store them in different units (chars vs pixels).  A graphics
frame leaving values equal to a following text frame's char counts
makes the text resize predicate compare equal, skipping the console
resize; the glyph loop then paints out of bounds of the surface.

Commit 95687639e6 (CVE-2026-17516) fixed the graphics-path consumer
of this confusion but not the text path.  Give vga_draw_text() its
own cache fields.

Fixes: CVE-2026-77913
Cc: [email protected]
Signed-off-by: Warisjeet Singh (sin99xx) <[email protected]>
---
 hw/display/vga.c     | 10 +++++++---
 hw/display/vga_int.h |  3 ++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/hw/display/vga.c b/hw/display/vga.c
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1241,7 +1241,7 @@
         return;
     }

-    if (width != s->last_width || height != s->last_height ||
+    if (width != s->last_text_width || height != s->last_text_height ||
         cw != s->last_cw || cheight != s->last_ch || s->last_depth) {
         s->last_scr_width = width * cw;
         s->last_scr_height = height * cheight;
@@ -1249,8 +1249,8 @@
         surface = qemu_console_surface(s->con);
         qemu_console_text_resize(s->con, width, height);
         s->last_depth = 0;
-        s->last_width = width;
-        s->last_height = height;
+        s->last_text_width = width;
+        s->last_text_height = height;
         s->last_ch = cheight;
         s->last_cw = cw;
         full_update = 1;
@@ -1845,6 +1845,8 @@

     s->last_width = -1;
     s->last_height = -1;
+    s->last_text_width = -1;
+    s->last_text_height = -1;
 }

 void vga_common_reset(VGACommonState *s)
@@ -1887,6 +1889,8 @@
     s->last_ch = 0;
     s->last_width = 0;
     s->last_height = 0;
+    s->last_text_width = 0;
+    s->last_text_height = 0;
     s->last_scr_width = 0;
     s->last_scr_height = 0;
     s->cursor_start = 0;
diff --git a/hw/display/vga_int.h b/hw/display/vga_int.h
--- a/hw/display/vga_int.h
+++ b/hw/display/vga_int.h
@@ -122,7 +122,8 @@
     uint32_t plane_updated;
     uint32_t last_line_offset;
     uint8_t last_cw, last_ch;
-    uint32_t last_width, last_height; /* in chars or pixels */
+    uint32_t last_width, last_height; /* in pixels (graphics renderer) */
+    uint32_t last_text_width, last_text_height; /* in chars (text renderer) */
     uint32_t last_scr_width, last_scr_height; /* in pixels */
     uint32_t last_depth; /* in bits */
     bool last_byteswap;