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From: Eric Dumazet <edumazet@google.com>
Date: Fri, 5 Apr 2024 18:30:26 +0200
Message-ID: <CANn89iJzJc+qNgwnEuzGReXqp6Gs7hWnex0_+f2CP9eTuohZyA@mail.gmail.com>
Subject: Re: [PATCH net] Bluetooth: validate setsockopt( BT_PKT_STATUS /
 BT_DEFER_SETUP) user input
To: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, 
	Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org, eric.dumazet@gmail.com, 
	syzbot <syzkaller@googlegroups.com>, Marcel Holtmann <marcel@holtmann.org>, 
	Johan Hedberg <johan.hedberg@gmail.com>, linux-bluetooth@vger.kernel.org
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On Fri, Apr 5, 2024 at 6:24=E2=80=AFPM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
ave used this so far (without risking a kernel bug)
>
> Fair enough, if we don't really have any risk of breaking the API
> (would result in using uninitialized memory) then I propose we do
> something like this:
>
> https://gist.github.com/Vudentz/c9092e8a3cb1e7e6a8fd384a51300eee
>
> That said perhaps copy_from_sockptr shall really take into account
> both source and destination lengths so it could incorporate the check
> e.g. if (dst_size > src_size) but that might result in changing every
> user of copy_from_sockptr thus I left it to be specific to bluetooth.

Make sure to return -EINVAL if the user provided length is too small,
not -EFAULT.