From 2b09d5d364986f724f17001ccfe4126b9b43a0be Mon Sep 17 00:00:00 2001 From: Samuel Thibault 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 Signed-off-by: Samuel Thibault Fixes: 2d2699d98492 ("fbcon: font setting should check limitation of driver") Cc: stable@vger.kernel.org Tested-by: Miko Larsson Reviewed-by: Greg Kroah-Hartman Signed-off-by: Helge Deller --- 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