netdev - Re: [PATCH bpf-next v8 3/6] libbpf: Add support for associating BPF program with struct

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Message-Id: <f7708afd314b93994ea6bef80b24442016742820e59f57bac0b793cddf37076d@mail.kernel.org>
Date: Wed,  3 Dec 2025 23:57:39 +0000 (UTC)
From: bot+bpf-ci@...nel.org
To: ameryhung@...il.com,bpf@...r.kernel.org
Cc: netdev@...r.kernel.org,alexei.starovoitov@...il.com,andrii@...nel.org,daniel@...earbox.net,tj@...nel.org,martin.lau@...nel.org,ameryhung@...il.com,kernel-team@...a.com,ast@...nel.org,andrii@...nel.org,daniel@...earbox.net,martin.lau@...nel.org,eddyz87@...il.com,yonghong.song@...ux.dev,clm@...a.com,ihor.solodrai@...ux.dev
Subject: Re: [PATCH bpf-next v8 3/6] libbpf: Add support for associating BPF program with struct_ops

> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index b66f5fbfb..21b57a629 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c

[ ... ]

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 706e7481b..076dc6b79 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -14137,6 +14137,37 @@ int bpf_program__set_attach_target(struct bpf_program *prog,
>  	return 0;
>  }
>
> +int bpf_program__assoc_struct_ops(struct bpf_program *prog, struct bpf_map *map,
> +				  struct bpf_prog_assoc_struct_ops_opts *opts)
> +{
> +	int prog_fd, map_fd;
> +
> +	prog_fd = bpf_program__fd(prog);
> +	if (prog_fd < 0) {
> +		pr_warn("prog '%s': can't associate BPF program without FD (was it loaded?)\n",
> +			prog->name);
                        ^^^^^^^^^^
Can this dereference prog->name when prog is NULL?  If prog is NULL,
bpf_program__fd() returns -EINVAL, entering this error path, but
prog->name dereferences the NULL pointer before the error can be
returned.

> +		return libbpf_err(-EINVAL);
> +	}
> +
> +	if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
> +		pr_warn("prog '%s': can't associate struct_ops program\n", prog->name);
                                                                        ^^^^^^^^^^
Same issue here - prog->name is dereferenced after we already know
prog_fd is invalid, which includes the case where prog is NULL.

> +		return libbpf_err(-EINVAL);
> +	}
> +
> +	map_fd = bpf_map__fd(map);
> +	if (map_fd < 0) {
> +		pr_warn("map '%s': can't associate BPF map without FD (was it created?)\n", map->name);
                                                                                             ^^^^^^^^^
Similar issue with map->name when map is NULL?  If map is NULL,
bpf_map__fd() returns -EINVAL, and then map->name is dereferenced.

> +		return libbpf_err(-EINVAL);
> +	}
> +
> +	if (!bpf_map__is_struct_ops(map)) {
> +		pr_warn("map '%s': can't associate non-struct_ops map\n", map->name);
                                                                         ^^^^^^^^^
And again here with map->name after checking the map is not a
struct_ops type.

> +		return libbpf_err(-EINVAL);
> +	}
> +
> +	return bpf_prog_assoc_struct_ops(prog_fd, map_fd, opts);
> +}
> +

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/19912520845