netdev - Re: [PATCH net] Bluetooth: validate setsockopt( BT_PKT_STATUS / BT_DEFER

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Message-ID: <CABBYNZK=oKCcMv8GEx__XiR+tSUwoTnwRkh2-6tJw1He9oGr6w@mail.gmail.com>
Date: Fri, 5 Apr 2024 13:38:37 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	syzbot <syzkaller@...glegroups.com>, Marcel Holtmann <marcel@...tmann.org>, 
	Johan Hedberg <johan.hedberg@...il.com>, linux-bluetooth@...r.kernel.org
Subject: Re: [PATCH net] Bluetooth: validate setsockopt( BT_PKT_STATUS /
 BT_DEFER_SETUP) user input

Hi Eric,

On Fri, Apr 5, 2024 at 12:30 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> On Fri, Apr 5, 2024 at 6:24 PM Luiz Augusto von Dentz
> <luiz.dentz@...il.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.

Sure, there was also a use of -EOVERFLOW and the fact we are using the
return of copy_from_sockptr so if it fails we just return -EFAULT
anyway, so if we do start returning the error from the like
bt_copy_from_sockptr then we better figure out the errors it returns
are proper.

Btw, do you want me to spin a new version containing these changes or
you would like to incorporate them into your patch and spin a v2?

-- 
Luiz Augusto von Dentz