Re: [PATCH bpf-next v10 3/8] bpf: Refactor reporting log_true_size for prog_load

[Leon Hwang]

On 12/2/26 06:10, Andrii Nakryiko wrote:
> On Wed, Feb 11, 2026 at 7:13 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
>>

[...]

>> @@ -6241,7 +6244,11 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size,
>>                 err = map_freeze(&attr);
>>                 break;
>>         case BPF_PROG_LOAD:
>> -               err = bpf_prog_load(&attr, uattr, size);
>> +               if (from_user && size >= offsetofend(union bpf_attr, log_true_size))
>> +                       log_true_size = uattr.user + offsetof(union bpf_attr, log_true_size);
> 
> LGTM, so
> 
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> 

Thanks for the review and the Ack!

> but it caught my eye that we will never return log_true_size if
> SYSCALL program tried to load another BPF program (light skeleton
> case), which seems limiting, but we can perhaps address that
> separately as a follow up
> 

Correct.

Currently, struct bpf_verifier_log and the log_true_size
back-propagation mechanism are designed specifically for user space and
are not compatible with in-kernel callers.

I’ll look into whether this can be improved in a follow-up.

Thanks,
Leon

[...]