From: Hou Tao <houtao1@huawei.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
Yonghong Song <yhs@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, KP Singh <kpsingh@kernel.org>,
<netdev@vger.kernel.org>, <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf-next 3/4] bpf: Fix net.core.bpf_jit_harden race
Date: Thu, 10 Mar 2022 09:01:46 +0800 [thread overview]
Message-ID: <06abdc4e-8806-10dd-c753-229d3e957add@huawei.com> (raw)
In-Reply-To: <20220309232253.v6oqev7jock7vm7i@ast-mbp.dhcp.thefacebook.com>
Hi,
On 3/10/2022 7:22 AM, Alexei Starovoitov wrote:
> On Wed, Mar 09, 2022 at 08:33:20PM +0800, Hou Tao wrote:
>> It is the bpf_jit_harden counterpart to commit 60b58afc96c9 ("bpf: fix
>> net.core.bpf_jit_enable race"). bpf_jit_harden will be tested twice
>> for each subprog if there are subprogs in bpf program and constant
>> blinding may increase the length of program, so when running
>> "./test_progs -t subprogs" and toggling bpf_jit_harden between 0 and 2,
>> jit_subprogs may fail because constant blinding increases the length
>> of subprog instructions during extra passs.
>>
>> So cache the value of bpf_jit_blinding_enabled() during program
>> allocation, and use the cached value during constant blinding, subprog
>> JITing and args tracking of tail call.
> Looks like this patch alone is enough.
> With race fixed. Patches 1 and 2 are no longer necessary, right?
Yes and no. With patch 3 applied, the problems described in patch 1 and patch 2
are gone, but it may recur due to other issue in JIT. So I post these two patch
together and hope these fixes can also be merged.
> .
next prev parent reply other threads:[~2022-03-10 1:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-09 12:33 [PATCH bpf-next 0/4] fixes for bpf_jit_harden race Hou Tao
2022-03-09 12:33 ` [PATCH bpf-next 1/4] bpf, x86: Fall back to interpreter mode when extra pass fails Hou Tao
2022-03-09 12:33 ` [PATCH bpf-next 2/4] bpf: Introduce bpf_int_jit_abort() Hou Tao
2022-03-11 23:54 ` Daniel Borkmann
2022-03-12 0:20 ` Daniel Borkmann
2022-03-09 12:33 ` [PATCH bpf-next 3/4] bpf: Fix net.core.bpf_jit_harden race Hou Tao
2022-03-09 23:22 ` Alexei Starovoitov
2022-03-10 1:01 ` Hou Tao [this message]
2022-03-10 3:29 ` Alexei Starovoitov
2022-03-10 3:48 ` Hou Tao
2022-03-09 12:33 ` [PATCH bpf-next 4/4] selftests/bpf: Test subprog jit when toggle bpf_jit_harden repeatedly Hou Tao
2022-03-16 22:30 ` [PATCH bpf-next 0/4] fixes for bpf_jit_harden race patchwork-bot+netdevbpf
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