From: David Miller <davem@davemloft.net>
To: glider@google.com
Cc: dvyukov@google.com, kcc@google.com, edumazet@google.com,
kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org
Subject: Re: [PATCH v2] net/packet: initialize val in packet_getsockopt()
Date: Tue, 25 Apr 2017 11:44:33 -0400 (EDT) [thread overview]
Message-ID: <20170425.114433.143144279134920277.davem@davemloft.net> (raw)
In-Reply-To: <20170424125914.43270-1-glider@google.com>
From: Alexander Potapenko <glider@google.com>
Date: Mon, 24 Apr 2017 14:59:14 +0200
> In the case getsockopt() is called with PACKET_HDRLEN and optlen < 4
> |val| remains uninitialized and the syscall may behave differently
> depending on its value. This doesn't have security consequences (as the
> uninit bytes aren't copied back), but it's still cleaner to initialize
> |val| and ensure optlen is not less than sizeof(int).
>
> This bug has been detected with KMSAN.
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> ---
> v2: - if len < sizeof(int), make it 0
No, you should signal an error if the len is too small.
Returning zero bytes to userspace silently makes the user think that
he got the data he asked for.
next prev parent reply other threads:[~2017-04-25 15:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-24 12:59 [PATCH v2] net/packet: initialize val in packet_getsockopt() Alexander Potapenko
2017-04-25 15:44 ` David Miller [this message]
2017-04-25 16:27 ` Alexander Potapenko
2017-04-25 16:32 ` David Miller
2017-04-25 16:38 ` Alexander Potapenko
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