From: David Miller <davem@davemloft.net>
To: jbacik@fb.com
Cc: jannh@google.com, ast@kernel.org, daniel@iogearbox.net,
netdev@vger.kernel.org
Subject: Re: [PATCH net][v2] bpf: fix range arithmetic for bpf map access
Date: Wed, 16 Nov 2016 13:22:31 -0500 (EST) [thread overview]
Message-ID: <20161116.132231.466321381115973145.davem@davemloft.net> (raw)
In-Reply-To: <1479156336-6211-1-git-send-email-jbacik@fb.com>
From: Josef Bacik <jbacik@fb.com>
Date: Mon, 14 Nov 2016 15:45:36 -0500
> I made some invalid assumptions with BPF_AND and BPF_MOD that could result in
> invalid accesses to bpf map entries. Fix this up by doing a few things
>
> 1) Kill BPF_MOD support. This doesn't actually get used by the compiler in real
> life and just adds extra complexity.
>
> 2) Fix the logic for BPF_AND, don't allow AND of negative numbers and set the
> minimum value to 0 for positive AND's.
>
> 3) Don't do operations on the ranges if they are set to the limits, as they are
> by definition undefined, and allowing arithmetic operations on those values
> could make them appear valid when they really aren't.
>
> This fixes the testcase provided by Jann as well as a few other theoretical
> problems.
>
> Reported-by: Jann Horn <jannh@google.com>
> Signed-off-by: Josef Bacik <jbacik@fb.com>
Applied, thanks.
prev parent reply other threads:[~2016-11-16 18:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-14 20:45 [PATCH net][v2] bpf: fix range arithmetic for bpf map access Josef Bacik
2016-11-15 3:10 ` Alexei Starovoitov
2016-11-15 13:47 ` Jann Horn
2016-11-15 14:20 ` Josef Bacik
2016-11-16 18:41 ` Jann Horn
2016-11-16 20:25 ` Josef Bacik
2016-11-16 20:26 ` Jann Horn
2016-11-16 18:22 ` David Miller [this message]
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