Re: [PATCH bpf 2/2] selftests/bpf: Test slices escaping a clone call frame

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Multi-line comments do not follow the strict BPF subsystem comment style.
--

commit 720f5969dc3c0d1bbc8d954089385b04bccca58f
Author: Xu Yunxiang <xyx2021@mail.ustc.edu.cn>

selftests/bpf: Test slices escaping a clone call frame

This commit adds a success case and a failure case to test BPF dynptr slice
behavior when a slice escapes a clone call frame. These tests verify that
subprogram return behaves correctly with respect to slice validity and
shared reference release.

> diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
> index 1cd61d72c166f..0704662cd32f3 100644
> --- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
> +++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
> @@ -1892,6 +1892,52 @@ int clone_invalidate4(void *ctx)
>  	return 0;
>  }
>  
> +static __noinline void clone_slice_in_subprog(struct bpf_dynptr *ptr, int **data)
> +{
> +	struct bpf_dynptr clone;
> +
> +	bpf_dynptr_clone(ptr, &clone);
> +	*data = bpf_dynptr_data(&clone, 0, sizeof(val));
> +}
> +
> +/* A slice that escapes the clone's call frame remains valid while the
> + * shared ringbuf reservation is live.
> + */

[Severity: Low]
This isn't a bug, but does this multi-line comment format match the BPF
subsystem requirements? The BPF guidelines specify that multi-line comments
must have the opening /* on its own line.

> +SEC("?raw_tp")
> +__success
> +int clone_slice_returned_frame_valid(void *ctx)
> +{
> +	struct bpf_dynptr ptr;
> +	int *data = NULL;
> +
> +	bpf_ringbuf_reserve_dynptr(&ringbuf, val, 0, &ptr);
> +	clone_slice_in_subprog(&ptr, &data);
> +	if (data)
> +		*data = 123;
> +	bpf_ringbuf_submit_dynptr(&ptr, 0);
> +
> +	return 0;
> +}
> +
> +/* Releasing the shared reservation must invalidate a slice that escaped
> + * from a clone's call frame.
> + */

[Severity: Low]
Similarly here, could this multi-line comment be updated so the text
starts on the next line after the opening /* marker?

> +SEC("?raw_tp")
> +__failure __msg("invalid mem access 'scalar'")
> +int clone_slice_returned_frame_invalid(void *ctx)
> +{

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260909042858.1734125-1-xyx2021@mail.ustc.edu.cn?part=2