From: Jiri Slaby <jirislaby@kernel.org>
To: Greg KH <gregkh@linuxfoundation.org>,
Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Daniel Vetter <daniel@ffwll.ch>, Helge Deller <deller@gmx.de>,
linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Sanan Hasanov <sanan.hasanov@knights.ucf.edu>
Subject: Re: [PATCH] fbcon: Check font dimension limits
Date: Thu, 26 Jan 2023 10:08:07 +0100 [thread overview]
Message-ID: <edcf26d4-64a0-04ea-435c-17d9efde7dd9@kernel.org> (raw)
In-Reply-To: <Y9IvBoAbmh27xl4B@kroah.com>
On 26. 01. 23, 8:43, Greg KH wrote:
>> --- linux-6.0.orig/drivers/video/fbdev/core/fbcon.c
>> +++ linux-6.0/drivers/video/fbdev/core/fbcon.c
>> @@ -2489,9 +2489,12 @@ static int fbcon_set_font(struct vc_data
>> 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 & (1U << (font->width - 1))) ||
>> + !(info->pixmap.blit_y & (1U << (font->height - 1))))
>
> Are you sure this is still needed with the above check added? If so,
> why? What is the difference in the compiled code?
For font->{width,height} == 32, definitely. IMO, 1 << 31 is undefined as
1 << 31 cannot be represented by an (signed) int.
--
js
suse labs
WARNING: multiple messages have this Message-ID (diff)
From: Jiri Slaby <jirislaby@kernel.org>
To: Greg KH <gregkh@linuxfoundation.org>,
Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: linux-fbdev@vger.kernel.org,
Sanan Hasanov <sanan.hasanov@knights.ucf.edu>,
Helge Deller <deller@gmx.de>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
stable@vger.kernel.org
Subject: Re: [PATCH] fbcon: Check font dimension limits
Date: Thu, 26 Jan 2023 10:08:07 +0100 [thread overview]
Message-ID: <edcf26d4-64a0-04ea-435c-17d9efde7dd9@kernel.org> (raw)
In-Reply-To: <Y9IvBoAbmh27xl4B@kroah.com>
On 26. 01. 23, 8:43, Greg KH wrote:
>> --- linux-6.0.orig/drivers/video/fbdev/core/fbcon.c
>> +++ linux-6.0/drivers/video/fbdev/core/fbcon.c
>> @@ -2489,9 +2489,12 @@ static int fbcon_set_font(struct vc_data
>> 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 & (1U << (font->width - 1))) ||
>> + !(info->pixmap.blit_y & (1U << (font->height - 1))))
>
> Are you sure this is still needed with the above check added? If so,
> why? What is the difference in the compiled code?
For font->{width,height} == 32, definitely. IMO, 1 << 31 is undefined as
1 << 31 cannot be represented by an (signed) int.
--
js
suse labs
next prev parent reply other threads:[~2023-01-26 9:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230126004911.869923511@ens-lyon.org>
2023-01-26 0:49 ` [PATCH] fbcon: Check font dimension limits Samuel Thibault
2023-01-26 0:49 ` Samuel Thibault
2023-01-26 0:51 ` Samuel Thibault
2023-01-26 0:51 ` Samuel Thibault
2023-01-26 7:43 ` Greg KH
2023-01-26 7:43 ` Greg KH
2023-01-26 9:08 ` Jiri Slaby [this message]
2023-01-26 9:08 ` Jiri Slaby
2023-01-29 15:13 ` Samuel Thibault
2023-01-29 15:13 ` Samuel Thibault
2023-01-26 9:02 ` Jiri Slaby
2023-01-26 9:02 ` Jiri Slaby
2023-01-29 15:04 ` Samuel Thibault
2023-01-29 15:04 ` Samuel Thibault
2023-01-28 1:32 ` kernel test robot
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