From: Yonghong Song <yhs@fb.com>
To: Johan Almbladh <johan.almbladh@anyfinetworks.com>,
<ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>
Cc: <kafai@fb.com>, <songliubraving@fb.com>,
<john.fastabend@gmail.com>, <kpsingh@kernel.org>,
<Tony.Ambardar@gmail.com>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>
Subject: Re: [PATCH] bpf: Fix off-by-one in tail call count limiting
Date: Wed, 28 Jul 2021 12:13:17 -0700 [thread overview]
Message-ID: <1503e9c4-7150-3244-4710-7b6b2d59e0da@fb.com> (raw)
In-Reply-To: <20210728164741.350370-1-johan.almbladh@anyfinetworks.com>
On 7/28/21 9:47 AM, Johan Almbladh wrote:
> Before, the interpreter allowed up to MAX_TAIL_CALL_CNT + 1 tail calls.
> Now precisely MAX_TAIL_CALL_CNT is allowed, which is in line with the
> behavior of the x86 JITs.
>
> Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
LGTM.
Acked-by: Yonghong Song <yhs@fb.com>
I also checked arm/arm64 jit. I saw the following comments:
/* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
* goto out;
* tail_call_cnt++;
*/
Maybe we have this MAX_TAIL_CALL_CNT + 1 issue
for arm/arm64 jit?
> ---
> kernel/bpf/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 9b1577498373..67682b3afc84 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -1559,7 +1559,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
>
> if (unlikely(index >= array->map.max_entries))
> goto out;
> - if (unlikely(tail_call_cnt > MAX_TAIL_CALL_CNT))
> + if (unlikely(tail_call_cnt >= MAX_TAIL_CALL_CNT))
> goto out;
>
> tail_call_cnt++;
>
next prev parent reply other threads:[~2021-07-28 19:13 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 8:17 [RFC PATCH 00/14] bpf/tests: Extend the eBPF test suite Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 01/14] bpf/tests: add BPF_JMP32 test cases Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 02/14] bpf/tests: add BPF_MOV tests for zero and sign extension Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 03/14] bpf/tests: fix typos in test case descriptions Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 04/14] bpf/tests: add more tests of ALU32 and ALU64 bitwise operations Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 05/14] bpf/tests: add more ALU32 tests for BPF_LSH/RSH/ARSH Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 06/14] bpf/tests: add more BPF_LSH/RSH/ARSH tests for ALU64 Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 07/14] bpf/tests: add more ALU64 BPF_MUL tests Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 08/14] bpf/tests: add tests for ALU operations implemented with function calls Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 09/14] bpf/tests: add word-order tests for load/store of double words Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 10/14] bpf/tests: add branch conversion JIT test Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 11/14] bpf/tests: add test for 32-bit context pointer argument passing Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 12/14] bpf/tests: add tests for atomic operations Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 13/14] bpf/tests: add tests for BPF_CMPXCHG Johan Almbladh
2021-07-26 8:17 ` [RFC PATCH 14/14] bpf/tests: add tail call test suite Johan Almbladh
2021-07-26 22:53 ` [RFC PATCH 00/14] bpf/tests: Extend the eBPF " Andrii Nakryiko
2021-07-28 8:27 ` Daniel Borkmann
2021-07-28 12:15 ` Johan Almbladh
2021-07-28 16:47 ` [PATCH] bpf: Fix off-by-one in tail call count limiting Johan Almbladh
2021-07-28 19:13 ` Yonghong Song [this message]
2021-07-29 21:37 ` Johan Almbladh
2021-07-29 22:29 ` Andrii Nakryiko
2021-07-29 22:48 ` Andrii Nakryiko
2021-08-01 8:37 ` Johan Almbladh
2021-08-02 20:28 ` Andrii Nakryiko
2021-08-05 14:37 ` Johan Almbladh
2021-08-05 22:54 ` Andrii Nakryiko
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