Commit dde7b3f5 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
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libbpf: Add explicit padding to bpf_xdp_set_link_opts 



Adding such anonymous padding fixes the issue with uninitialized portions of
bpf_xdp_set_link_opts when using LIBBPF_DECLARE_OPTS macro with inline field
initialization:

DECLARE_LIBBPF_OPTS(bpf_xdp_set_link_opts, opts, .old_fd = -1);

When such code is compiled in debug mode, compiler is generating code that
leaves padding bytes uninitialized, which triggers error inside libbpf APIs
that do strict zero initialization checks for OPTS structs.

Adding anonymous padding field fixes the issue.

Fixes: bd5ca3ef ("libbpf: Add function to set link XDP fd while specifying old program")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210313210920.1959628-2-andrii@kernel.org
parent 4d0b9389

tools/lib/bpf/libbpf.h

+1 −0
Original line number Diff line number Diff line
@@ -507,6 +507,7 @@ struct xdp_link_info { 
struct bpf_xdp_set_link_opts {

	size_t sz;

	int old_fd;

	size_t :0;

};

#define bpf_xdp_set_link_opts__last_field old_fd