netdev - Re: [PATCH] net/socket: Ensure length of input socket option param >= sizeof(int)

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Message-ID: <CABBYNZJ2hGRAaPOkyC8vHrsqNtfMS2N4cMAMQTY6M9gdYdthog@mail.gmail.com>
Date: Tue, 9 Apr 2024 09:25:56 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Edward Adam Davis <eadavis@...com>, pmenzel@...gen.mpg.de, edumazet@...gle.com, 
	netdev@...r.kernel.org, johan.hedberg@...il.com, 
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org, 
	marcel@...tmann.org, syzbot+d4ecae01a53fd9b42e7d@...kaller.appspotmail.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] net/socket: Ensure length of input socket option param >= sizeof(int)

Hi,

On Tue, Apr 9, 2024 at 9:07 AM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
> On 4/9/24 14:15, Edward Adam Davis wrote:
> > The optlen value passed by syzbot to _sys_setsockopt() is 2, which results in
> > only 2 bytes being allocated when allocating memory to kernel_optval, and the
> > optval size passed when calling the function copy_from_sockptr() is 4 bytes.
> > Here, optlen is determined uniformly in the entry function __sys_setsockopt().
> > If its value is less than 4, the parameter is considered invalid.
> >
> > Reported-by: syzbot+837ba09d9db969068367@...kaller.appspotmail.com
> > Reported-by: syzbot+b71011ec0a23f4d15625@...kaller.appspotmail.com
> > Reported-by: syzbot+d4ecae01a53fd9b42e7d@...kaller.appspotmail.com
> > Signed-off-by: Edward Adam Davis <eadavis@...com>
>
>
> I think I gave my feedback already.
>
> Please do not ignore maintainers feedback.
>
> This patch is absolutely wrong.
>
> Some setsockopt() deal with optlen == 1 just fine, thank you very much.

+1, I don't think the setsockopt interface has a fixed minimum of
sizeof(int), so this is a nak from me as well.

-- 
Luiz Augusto von Dentz