linux-kernel - Re: [PATCHv2] fbcon: Check font dimension limits

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Message-ID: <5fcd25ee-07bb-6eab-3e73-22680a0104bf@gmx.de>
Date:   Sat, 4 Feb 2023 14:31:22 +0100
From:   Helge Deller <deller@....de>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Samuel Thibault <samuel.thibault@...-lyon.org>,
        Daniel Vetter <daniel@...ll.ch>, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org,
        Sanan Hasanov <sanan.hasanov@...ghts.ucf.edu>
Subject: Re: [PATCHv2] fbcon: Check font dimension limits

On 1/31/23 15:51, Greg KH wrote:
> On Sun, Jan 29, 2023 at 04:17:40PM +0100, Samuel Thibault wrote:
>> 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@...ghts.ucf.edu>
>> Signed-off-by: Samuel Thibault <samuel.thibault@...-lyon.org>
>> Fixes: 2d2699d98492 ("fbcon: font setting should check limitation of driver")
>> Cc: stable@...r.kernel.org
>
> Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

applied to fbdev git tree.

Thanks!
Helge