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Date: Sat, 7 Oct 2023 13:30:54 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: FUJITA Tomonori <fujita.tomonori@gmail.com>
Cc: tmgross@umich.edu, netdev@vger.kernel.org,
	rust-for-linux@vger.kernel.org, andrew@lunn.ch,
	miguel.ojeda.sandonis@gmail.com
Subject: Re: [PATCH v2 1/3] rust: core abstractions for network PHY drivers
Message-ID: <2023100728-unloving-snowboard-d558@gregkh>
References: <CALNs47sdj2onJS3wFUVoONYL_nEgT+PTLTVuMLcmE6W6JgZAXA@mail.gmail.com>
 <20231007.195857.292080693191739384.fujita.tomonori@gmail.com>
 <2023100757-crewman-mascot-bc1d@gregkh>
 <20231007.202324.2257155764500021886.fujita.tomonori@gmail.com>
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In-Reply-To: <20231007.202324.2257155764500021886.fujita.tomonori@gmail.com>

On Sat, Oct 07, 2023 at 08:23:24PM +0900, FUJITA Tomonori wrote:
> On Sat, 7 Oct 2023 13:17:13 +0200
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Sat, Oct 07, 2023 at 07:58:57PM +0900, FUJITA Tomonori wrote:
> >> > Since we're taking user input, it probably doesn't hurt to do some
> >> > sort of sanity check rather than casting. Maybe warn once then return
> >> > the biggest nowrapping value
> >> > 
> >> >     let speed_i32 = i32::try_from(speed).unwrap_or_else(|_| {
> >> >         warn_once!("excessive speed {speed}");
> > 
> > NEVER call WARN() on user input, as you now just rebooted the machine
> > and caused a DoS (and syzbot will start to spam you with reports.)
> 
> Trevor uses `user` as the user of this function, which is a PHY driver.
> 

Ok, same thing in a way, just do a dev_warn() and return an error, no
need to do a full traceback splat at all.

thanks,

greg k-h