Re: [PATCH bpf-next v2 14/20] libbpf: Add cleanup_info to bpf_prog_load_opts

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] libbpf: missing E2BIG fallback for cleanup_info breaks forward compatibility
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commit d67b69538e39a329708fcc9fa943f0ad05afaa05
Author: Yonghong Song <yonghong.song@linux.dev>

libbpf: Add cleanup_info to bpf_prog_load_opts

Let a caller hand the kernel an exception cleanup table. Extend struct
bpf_prog_load_opts with cleanup_info, cleanup_info_cnt and
cleanup_info_rec_size, pass them through to BPF_PROG_LOAD, and grow the
attr size bpf_prog_load() computes to cover the new fields.

> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 96819c082c772..bcf490570961c 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
[ ... ]
> @@ -370,6 +370,10 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
>  	attr.fd_array = ptr_to_u64(OPTS_GET(opts, fd_array, NULL));
>  	attr.fd_array_cnt = OPTS_GET(opts, fd_array_cnt, 0);
>  
> +	attr.cleanup_info = ptr_to_u64(OPTS_GET(opts, cleanup_info, NULL));
> +	attr.cleanup_info_cnt = OPTS_GET(opts, cleanup_info_cnt, 0);
> +	attr.cleanup_info_rec_size = OPTS_GET(opts, cleanup_info_rec_size, 0);

[Severity: Medium]
Will this break forward compatibility for bpf_prog_load() if cleanup_info
triggers an -E2BIG error?

Later in bpf_prog_load(), there is a retry loop to handle -E2BIG when the
userspace-provided record size is larger than what the kernel supports:

	while (errno == E2BIG && (!finfo || !linfo)) {
		if (!finfo && attr.func_info_cnt &&
		    attr.func_info_rec_size < func_info_rec_size) {
            /* try with corrected func info records */
            ...

The loop condition and body don't seem to include checks for cleanup_info.

If the kernel returns -E2BIG because of a larger cleanup_info_rec_size,
won't this hit the else { break; } block or skip the loop entirely, causing
the load to fail instead of retrying with truncated records?

> +
>  	if (log_level) {
>  		attr.log_buf = ptr_to_u64(log_buf);
>  		attr.log_size = log_size;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260918044156.3283973-1-yonghong.song@linux.dev?part=14