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Date: Wed, 1 Apr 2026 17:49:56 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Hangbin Liu <liuhangbin@gmail.com>
Cc: Donald Hunter <donald.hunter@gmail.com>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, Simon Horman <horms@kernel.org>, Andrew Lunn
 <andrew@lunn.ch>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/4] ethtool: strset: check nla_len overflow
 before nla_nest_end
Message-ID: <20260401174956.1e526940@kernel.org>
In-Reply-To: <aczI7FfIScrKhBGQ@fedora>
References: <20260331-b4-ynl_ethtool-v1-0-dda2a9b55df8@gmail.com>
	<20260331-b4-ynl_ethtool-v1-3-dda2a9b55df8@gmail.com>
	<20260331184637.58b968ef@kernel.org>
	<aczI7FfIScrKhBGQ@fedora>
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On Wed, 1 Apr 2026 07:27:40 +0000 Hangbin Liu wrote:
> On Tue, Mar 31, 2026 at 06:46:37PM -0700, Jakub Kicinski wrote:
> > On Tue, 31 Mar 2026 11:56:13 +0800 Hangbin Liu wrote:  
> > > +		if (skb_tail_pointer(skb) - (unsigned char *)strings_attr > U16_MAX)
> > > +			goto nla_put_failure;  
> > 
> > bit ugly, let's add a variant of nla_nest_end() which can return 
> > an error on overflow (without the warning from patch 4) ?  
> 
> I was tried to not touch nla_nest_end() as it is used everywhere. But it makes
> sense to me to add a new function to check this. I'm not very good at naming,
> maybe `nla_nest_end_validate()` ? Or any other name if you have?

I was thinking nla_nest_end_check() to match the __must_check
attribute. But I also like nla_nest_end_safe()
_validate() is a little long but anything <=5 chars is fine.