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From: Greg KH <gregkh@linuxfoundation.org>
To: Xianting Tian <xianting.tian@linux.alibaba.com>
Cc: virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, arnd@arndb.de, amit@kernel.org
Subject: Re: [RESEND][PATCH] virtio_console: protect max_nr_ports to avoid invalid value
Date: Fri, 27 Aug 2021 11:00:21 +0200	[thread overview]
Message-ID: <YSippdinb67QYU6K@kroah.com> (raw)
In-Reply-To: <20210820075219.202404-1-xianting.tian@linux.alibaba.com>

On Fri, Aug 20, 2021 at 03:52:19PM +0800, Xianting Tian wrote:
> In theory untrusted remote host can pass a big or overflow value
> of max_nr_ports to guest, it may cause guest system consumes
> a lot of memory when create vqs and other impacts.

How can you have a untrusted host?  Can't they do a lot worse things
than just this?

> 
> Add the protection to guarantee max_nr_ports to get a safe value.
> 
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
> ---
>  drivers/char/virtio_console.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 7eaf303a7..bba985c81 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -29,6 +29,8 @@
>  
>  #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
>  
> +#define MAX_NR_PORTS	MAX_NR_HVC_CONSOLES

How was this value picked?

thanks,

greg k-h
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Virtualization@lists.linux-foundation.org
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WARNING: multiple messages have this Message-ID (diff)
From: Greg KH <gregkh@linuxfoundation.org>
To: Xianting Tian <xianting.tian@linux.alibaba.com>
Cc: amit@kernel.org, arnd@arndb.de,
	virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RESEND][PATCH] virtio_console: protect max_nr_ports to avoid invalid value
Date: Fri, 27 Aug 2021 11:00:21 +0200	[thread overview]
Message-ID: <YSippdinb67QYU6K@kroah.com> (raw)
In-Reply-To: <20210820075219.202404-1-xianting.tian@linux.alibaba.com>

On Fri, Aug 20, 2021 at 03:52:19PM +0800, Xianting Tian wrote:
> In theory untrusted remote host can pass a big or overflow value
> of max_nr_ports to guest, it may cause guest system consumes
> a lot of memory when create vqs and other impacts.

How can you have a untrusted host?  Can't they do a lot worse things
than just this?

> 
> Add the protection to guarantee max_nr_ports to get a safe value.
> 
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
> ---
>  drivers/char/virtio_console.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 7eaf303a7..bba985c81 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -29,6 +29,8 @@
>  
>  #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
>  
> +#define MAX_NR_PORTS	MAX_NR_HVC_CONSOLES

How was this value picked?

thanks,

greg k-h

  parent reply	other threads:[~2021-08-27  9:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20  7:52 [RESEND][PATCH] virtio_console: protect max_nr_ports to avoid invalid value Xianting Tian
2021-08-23 11:55 ` Xianting TIan
2021-08-27  9:00 ` Greg KH [this message]
2021-08-27  9:00   ` Greg KH

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