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From: Johan Almbladh <johan.almbladh@anyfinetworks.com>
To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org
Cc: kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	john.fastabend@gmail.com, kpsingh@kernel.org,
	Tony.Ambardar@gmail.com, netdev@vger.kernel.org,
	bpf@vger.kernel.org,
	Johan Almbladh <johan.almbladh@anyfinetworks.com>
Subject: [PATCH] bpf: Fix off-by-one in tail call count limiting
Date: Wed, 28 Jul 2021 18:47:41 +0200	[thread overview]
Message-ID: <20210728164741.350370-1-johan.almbladh@anyfinetworks.com> (raw)
In-Reply-To: <5afe26c6-7ab1-88ab-a3e0-eb007256a856@iogearbox.net>

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>
---
 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++;
-- 
2.25.1


  parent reply	other threads:[~2021-07-28 16:48 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     ` Johan Almbladh [this message]
2021-07-28 19:13       ` [PATCH] bpf: Fix off-by-one in tail call count limiting Yonghong Song
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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