linux-kernel - Re: [PATCH net] ptp: limit number of virtual clocks per physical clock

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Message-ID: <c6547053-7de2-42a2-b8f7-6837e9ab85ca@redhat.com>
Date: Tue, 7 Jan 2025 13:04:02 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Thomas Weißschuh <linux@...ssschuh.net>,
 Richard Cochran <richardcochran@...il.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Yangbo Lu <yangbo.lu@....com>
Cc: Al Viro <viro@...iv.linux.org.uk>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, cheung wall <zzqq0103.hey@...il.com>,
 stable@...r.kernel.org
Subject: Re: [PATCH net] ptp: limit number of virtual clocks per physical
 clock

On 1/3/25 2:40 PM, Thomas Weißschuh wrote:
> The sysfs interface can be used to trigger arbitrarily large memory
> allocations. This can induce pressure on the VM layer to satisfy the
> request only to fail anyways.
> 
> Reported-by: cheung wall <zzqq0103.hey@...il.com>
> Closes: https://lore.kernel.org/lkml/20250103091906.GD1977892@ZenIV/
> Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion")
> Cc: stable@...r.kernel.org
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
> The limit is completely made up, let me know if there is something
> better.

I'm also unsure if such constant value is reasonable for all the
use-cases. Any additional feedback more than welcome.

In any case, I guess it would make sense to update
Documentation/ABI/testing/sysfs-ptp accordingly.

Thanks,

Paolo