Re: [PATCH bpf-next v6 10/12] selftests/bpf: Add tests to verify verifier log for global percpu data

[Leon Hwang <leon.hwang@linux.dev>]

On 15/6/26 23:40, sashiko-bot@kernel.org wrote:
[...]
>> +SEC("?kprobe")
>> +__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
>> +int verifier_snprintf(void *ctx)
>> +{
>> +	u64 args[] = { data };
>> +	char buf[128];
>> +	int len;
>> +
>> +	len = bpf_snprintf(buf, sizeof(buf), fmt, args, 1);
> 
> [Severity: Low]
> Should this be passing sizeof(args) instead of 1?
> 
> The bpf_snprintf helper requires data_len to be the size of the data array
> in bytes. Passing 1 makes the test brittle if the verifier's argument
> evaluation order changes in the future, as it would fail on the data_len
> argument before checking the fmt argument.
> 
Will use sizeof(args).

Thanks,
Leon