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: fbcon: Check font dimension limits

Git-commit: 2b09d5d364986f724f17001ccfe4126b9b43a0be

Patch-mainline: v6.2-rc7

References: bsc#1154048

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>

Acked-by: Thomas Zimmermann <tzimmermann@suse.com>

---

 drivers/video/console/fbcon.c | 7 +++++--

 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c

index 14a7d404062c..1b14c21af2b7 100644

--- a/drivers/video/console/fbcon.c

+++ b/drivers/video/console/fbcon.c

@@ -2495,9 +2495,12 @@ static int fbcon_set_font(struct vc_data *vc, struct console_font *font,

 	    h > FBCON_SWAP(info->var.rotate, info->var.yres, info->var.xres))

 		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))))

+	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 */

-- 

2.40.1