netdev - Re: [RFC PATCH bpf-next v3 02/12] bpf: initial support for attaching struct ops to cgroups

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Message-Id: <b0f009e6e0f8ec688597c5c3954b3335069f3aa60441a7c3f44246af7a9c4629@mail.kernel.org>
Date: Fri, 23 Jan 2026 09:19:05 +0000 (UTC)
From: bot+bpf-ci@...nel.org
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Subject: Re: [RFC PATCH bpf-next v3 02/12] bpf: initial support for attaching struct ops to cgroups

> diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
> index de01cf3025b3..f575c5cd0dc8 100644

[ ... ]

> @@ -1377,6 +1378,18 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
>  	}
>  	bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_map_lops, NULL,
>  		      attr->link_create.attach_type);
> +#ifdef CONFIG_CGROUPS
> +	if (attr->link_create.cgroup.relative_fd) {
> +		struct cgroup *cgrp;
> +
> +		cgrp = cgroup_get_from_fd(attr->link_create.cgroup.relative_fd);
> +		if (IS_ERR(cgrp))
> +			return PTR_ERR(cgrp);
                        ^^^^^^^^^^^^^^^^^

When cgroup_get_from_fd() fails, this returns directly without cleaning
up. At this point in bpf_struct_ops_link_create(), link has already been
allocated via kzalloc() and map has a reference from bpf_map_get().

Should this use goto err_out instead? The err_out label calls
bpf_map_put(map) and kfree(link), which would be needed here but are
bypassed by the direct return.

> +
> +		link->cgroup_id = cgroup_id(cgrp);
> +		cgroup_put(cgrp);
> +	}
> +#endif /* CONFIG_CGROUPS */
>
>  	err = bpf_link_prime(&link->link, &link_primer);
>  	if (err)


---
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/21280790825