From: Daniel Borkmann <daniel@iogearbox•net>
To: Josef Bacik <jbacik@fb•com>,
davem@davemloft•net, netdev@vger•kernel.org, ast@kernel•org,
jannh@google•com, kernel-team@fb•com
Subject: Re: [PATCH net][v2] bpf: fix states equal logic for varlen access
Date: Tue, 29 Nov 2016 20:09:37 +0100 [thread overview]
Message-ID: <583DD271.2020900@iogearbox.net> (raw)
In-Reply-To: <1480440429-2531-1-git-send-email-jbacik@fb.com>
On 11/29/2016 06:27 PM, Josef Bacik wrote:
> If we have a branch that looks something like this
>
> int foo = map->value;
> if (condition) {
> foo += blah;
> } else {
> foo = bar;
> }
> map->array[foo] = baz;
>
> We will incorrectly assume that the !condition branch is equal to the condition
> branch as the register for foo will be UNKNOWN_VALUE in both cases. We need to
> adjust this logic to only do this if we didn't do a varlen access after we
> processed the !condition branch, otherwise we have different ranges and need to
> check the other branch as well.
>
> Fixes: 484611357c19 ("bpf: allow access into map value arrays")
> Reported-by: Jann Horn <jannh@google•com>
> Signed-off-by: Josef Bacik <jbacik@fb•com>
Acked-by: Daniel Borkmann <daniel@iogearbox•net>
next prev parent reply other threads:[~2016-11-29 19:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-29 17:27 [PATCH net][v2] bpf: fix states equal logic for varlen access Josef Bacik
2016-11-29 18:52 ` Alexei Starovoitov
2016-11-29 19:09 ` Daniel Borkmann [this message]
2016-11-30 19:51 ` David Miller
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