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bpf: Fix off-by-one in tail call count limiting

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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>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210728164741.350370-1-johan.almbladh@anyfinetworks.com
This commit is contained in:
Johan Almbladh 2021-07-28 18:47:41 +02:00 committed by Andrii Nakryiko
parent 7cdd0a89ec
commit b61a28cf11
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/core.c
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@ -1562,7 +1562,7 @@ 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++;