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From: Khalid Masum <khalid.masum.92@gmail.com>
To: Helge Deller <deller@gmx.de>,
	syzbot <syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com>,
	dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>
Subject: Re: [PATCH] vt: Clear selection before changing the font
Date: Sun, 31 Jul 2022 17:32:41 +0600	[thread overview]
Message-ID: <166886f8-eb9e-f779-cf57-1ea353adc446@gmail.com> (raw)
In-Reply-To: <YuV9apZGNmGfjcor@p100>

On 7/31/22 00:50, Helge Deller wrote:
> When changing the console font with ioctl(KDFONTOP) the new font size
> can be bigger than the previous font. A previous selection may thus now
> be outside of the new screen size and thus trigger out-of-bounds
> accesses to graphics memory if the selection is removed in
> vc_do_resize().
> 
> Prevent such out-of-memory accesses by dropping the selection before the
> various con_font_set() console handlers are called.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>

Tested-by: Khalid Masum <khalid.masum.92@gmail.com>

> Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com
> 
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index dfc1f4b445f3..3f09205185a4 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -4662,9 +4662,11 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op)
>   	console_lock();
>   	if (vc->vc_mode != KD_TEXT)
>   		rc = -EINVAL;
> -	else if (vc->vc_sw->con_font_set)
> +	else if (vc->vc_sw->con_font_set) {
> +		if (vc_is_sel(vc))
> +			clear_selection();
>   		rc = vc->vc_sw->con_font_set(vc, &font, op->flags);
> -	else
> +	} else
>   		rc = -ENOSYS;
>   	console_unlock();
>   	kfree(font.data);
> @@ -4691,9 +4693,11 @@ static int con_font_default(struct vc_data *vc, struct console_font_op *op)
>   		console_unlock();
>   		return -EINVAL;
>   	}
> -	if (vc->vc_sw->con_font_default)
> +	if (vc->vc_sw->con_font_default) {
> +		if (vc_is_sel(vc))
> +			clear_selection();
>   		rc = vc->vc_sw->con_font_default(vc, &font, s);
> -	else
> +	} else
>   		rc = -ENOSYS;
>   	console_unlock();
>   	if (!rc) {

  reply	other threads:[~2022-07-31 11:32 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-19  9:18 [syzbot] KASAN: vmalloc-out-of-bounds Write in imageblit (2) syzbot
2022-01-20 22:58 ` syzbot
2022-01-21  1:48 ` syzbot
2022-07-29  6:51 ` Khalid Masum
2022-07-30 17:25   ` Helge Deller
2022-07-30 18:49     ` [PATCH] tty: vt: selection: Add check for valid tiocl_selection values Helge Deller
2022-08-04  5:47       ` Jiri Slaby
2022-08-04  7:15         ` Helge Deller
2022-08-04  8:44           ` Helge Deller
2022-08-04  9:22             ` Jiri Slaby
2022-08-05 11:13               ` Adam Borowski
2022-07-30 18:50     ` [PATCH] vt: Clear selection before changing the font Helge Deller
2022-07-31 11:32       ` Khalid Masum [this message]
2022-07-31 10:03     ` [syzbot] KASAN: vmalloc-out-of-bounds Write in imageblit (2) Khalid Masum
2022-07-31 10:54       ` Helge Deller
2022-07-31 11:23         ` Khalid Masum
2022-07-31 13:55     ` Khalid Masum
2022-07-31 15:39       ` Helge Deller
2022-08-01  4:09         ` Khalid Masum
2022-07-30  8:12 ` Khalid Masum
2022-07-30 10:55   ` syzbot
2022-08-01 10:43   ` Dan Carpenter
2022-08-01 14:06     ` Khalid Masum
2022-07-30 11:45 ` Khalid Masum
2022-07-30 15:39   ` syzbot

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