tools/testing/selftests/bpf/progs/cgroup_storage.c

File Facts

System

Linux kernel

Corpus path

tools/testing/selftests/bpf/progs/cgroup_storage.c

Extension

.c

Size

1674 bytes

Lines

68

Domain

Support Tooling And Documentation

Bucket

tools

Inferred role

Support Tooling And Documentation: implementation source

Status

source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/bpf.h
• bpf/bpf_helpers.h

Detected Declarations

• function bpf_prog
• function trigger_oob

Annotated Snippet

SEC("cgroup/sock_create")
int trigger_oob(struct bpf_sock *sk)
{
	__u32 key = 0;
	__u32 *cgroup_val;
	__u32 value = 0x12345678;

	/* Get cgroup storage value */
	cgroup_val = bpf_get_local_storage(&cgroup_storage_oob, 0);
	if (!cgroup_val)
		return 0;

	/* Initialize cgroup storage */
	*cgroup_val = value;

	/* This triggers the OOB read:
	 * bpf_map_update_elem() -> htab_map_update_elem() ->
	 * pcpu_init_value() -> copy_map_value_long() ->
	 * bpf_obj_memcpy(..., long_memcpy=true) ->
	 * bpf_long_memcpy(dst, src, round_up(4, 8))
	 *
	 * The copy size is rounded up to 8 bytes, but cgroup_val
	 * points to a 4-byte buffer, causing a 4-byte OOB read.
	 */
	bpf_map_update_elem(&lru_map, &key, cgroup_val, BPF_ANY);

	return 1;
}

char _license[] SEC("license") = "GPL";

Annotation

• Immediate include surface: `linux/bpf.h`, `bpf/bpf_helpers.h`.
• Detected declarations: `function bpf_prog`, `function trigger_oob`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.