In the Linux kernel, the following vulnerability has been resolved: bpf: Preserve unique-field state across nested structs btf_find_struct_field() initializes a fresh seen mask for every recursive descent. Unique special fields in different levels of the same aggregate therefore do not see one another. The duplicate fields can reach btf_parse_fields(), where they trigger an invariant WARN_ON_ONCE(). A crafted user BTF can consequently trigger the warning before map creation checks capabilities. Initialize the seen mask once in btf_find_field() and pass the same pointer through struct, datasec, and nested-struct walks. This gives the entire field traversal one shared uniqueness state.
https://git.kernel.org/stable/c/f08619f060468076e4acbdc10e0713af20d60e65
https://git.kernel.org/stable/c/cec97102d4147e18568c93946014c4c8ebf86fcf
https://git.kernel.org/stable/c/373a1e9366e711b89bc5e45bd6edf33ef62402cd
https://git.kernel.org/stable/c/28d5f20ed022ade0fb0bfbf50b78fec782083175