Re: [PATCH bpf-next v7 2/2] bpf: Reject programs with inlined helpers if JIT is unavailable

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The patch prevents loading BPF programs that use JIT-inlined helpers (e.g., `bpf_get_smp_processor_id`) when the BPF JIT is explicitly disabled at load time (`net.core.bpf_jit_enable=0`).
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commit 01713d8606e656f4dadefe493f371f4c861d842b
Author: Tiezhu Yang <yangtiezhu@loongson.cn>

bpf: Reject programs with inlined helpers if JIT is unavailable

This patch sets the jit_required flag to 1 when a BPF program uses helpers
that are expected to be inlined by the JIT compiler. This prevents a kernel
panic in the BPF interpreter by rejecting the program with -ENOTSUPP if
JIT compilation is unavailable at runtime.

> diff --git a/kernel/bpf/fixups.c b/kernel/bpf/fixups.c
> index 12a8a4eb757f1..94e0457a0aa33 100644
> --- a/kernel/bpf/fixups.c
> +++ b/kernel/bpf/fixups.c
> @@ -1841,8 +1841,10 @@ int bpf_do_misc_fixups(struct bpf_verifier_env *env)
>  		}
>  
>  		/* Skip inlining the helper call if the JIT does it. */
> -		if (bpf_jit_inlines_helper_call(insn->imm))
> +		if (bpf_jit_inlines_helper_call(insn->imm)) {
> +			prog->jit_required = 1;
>  			goto next_insn;
> +		}

[Severity: High]
While this correctly prevents the interpreter panic, does this unconditionally
reject valid BPF programs when the JIT is explicitly disabled at load time
(e.g., net.core.bpf_jit_enable=0)?

If this block checked prog->jit_requested before skipping the fixup and
setting jit_required, wouldn't the verifier properly patch the instruction
when JIT is disabled, allowing the program to execute successfully in the
interpreter?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260702143656.28845-1-yangtiezhu@loongson.cn?part=2