From: Daniel Borkmann <daniel@iogearbox.net>
To: Alexei Starovoitov <ast@fb.com>,
"David S . Miller" <davem@davemloft.net>
Cc: Gianluca Borello <g.borello@gmail.com>, netdev@vger.kernel.org
Subject: Re: [PATCH net-next] bpf: Preserve const register type on const OR alu ops
Date: Sun, 04 Dec 2016 00:41:59 +0100 [thread overview]
Message-ID: <58435847.2000406@iogearbox.net> (raw)
In-Reply-To: <1480797093-1050393-1-git-send-email-ast@fb.com>
On 12/03/2016 09:31 PM, Alexei Starovoitov wrote:
> From: Gianluca Borello <g.borello@gmail.com>
>
> Occasionally, clang (e.g. version 3.8.1) translates a sum between two
> constant operands using a BPF_OR instead of a BPF_ADD. The verifier is
> currently not handling this scenario, and the destination register type
> becomes UNKNOWN_VALUE even if it's still storing a constant. As a result,
> the destination register cannot be used as argument to a helper function
> expecting a ARG_CONST_STACK_*, limiting some use cases.
>
> Modify the verifier to handle this case, and add a few tests to make sure
> all combinations are supported, and stack boundaries are still verified
> even with BPF_OR.
>
> Signed-off-by: Gianluca Borello <g.borello@gmail.com>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
next prev parent reply other threads:[~2016-12-03 23:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-03 20:31 [PATCH net-next] bpf: Preserve const register type on const OR alu ops Alexei Starovoitov
2016-12-03 23:41 ` Daniel Borkmann [this message]
2016-12-05 18:41 ` David Miller
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