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From 2b09d5d364986f724f17001ccfe4126b9b43a0be Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sun, 29 Jan 2023 16:17:40 +0100
Subject: [PATCH] fbcon: Check font dimension limits
blit_x and blit_y are u32, so fbcon currently cannot support fonts
larger than 32x32.
The 32x32 case also needs shifting an unsigned int, to properly set bit
31, otherwise we get "UBSAN: shift-out-of-bounds in fbcon_set_font",
as reported on:
http://lore.kernel.org/all/IA1PR07MB98308653E259A6F2CE94A4AFABCE9@IA1PR07MB9830.namprd07.prod.outlook.com
Kernel Branch: 6.2.0-rc5-next-20230124
Kernel config: https://drive.google.com/file/d/1F-LszDAizEEH0ZX0HcSR06v5q8FPl2Uv/view?usp=sharing
Reproducer: https://drive.google.com/file/d/1mP1jcLBY7vWCNM60OMf-ogw-urQRjNrm/view?usp=sharing
Reported-by: Sanan Hasanov <sanan.hasanov@Knights.ucf.edu>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Fixes: 2d2699d98492 ("fbcon: font setting should check limitation of driver")
Cc: stable@vger.kernel.org
Tested-by: Miko Larsson <mikoxyzzz@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Helge Deller <deller@gmx.de>
---
drivers/video/fbdev/core/fbcon.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 22bb3892f6bd..74f508ec8d4c 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2434,11 +2434,13 @@ static int fbcon_set_font(struct vc_data *vc, struct console_font *font,
* If not this check should be changed to charcount < 256 */
if (charcount != 256 && charcount != 512)
return -EINVAL;
+ if (font->width > 32 || font->height > 32)
+ return -EINVAL;
/* Make sure drawing engine can handle the font */
- if (!(info->pixmap.blit_x & (1 << (font->width - 1))) ||
- !(info->pixmap.blit_y & (1 << (font->height - 1))))
- return -EINVAL;
+ if (!(info->pixmap.blit_x & BIT(font->width - 1)) ||
+ !(info->pixmap.blit_y & BIT(font->height - 1)))
+ return -EINVAL;
/* Make sure driver can handle the font length */
if (fbcon_invalid_charcount(info, charcount))
--
2.34.1
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