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Commit 1d4126c4 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
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libbpf: sanitize VAR to conservative 1-byte INT 



If VAR in non-sanitized BTF was size less than 4, converting such VAR
into an INT with size=4 will cause BTF validation failure due to
violationg of STRUCT (into which DATASEC was converted) member size.
Fix by conservatively using size=1.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 04efe591

tools/lib/bpf/libbpf.c

+7 −2
Original line number Diff line number Diff line
@@ -1377,8 +1377,13 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj) 
		if (!has_datasec && kind == BTF_KIND_VAR) {

			/* replace VAR with INT */

			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);

			t->size = sizeof(int);

			*(int *)(t+1) = BTF_INT_ENC(0, 0, 32);

			/*

			 * using size = 1 is the safest choice, 4 will be too

			 * big and cause kernel BTF validation failure if

			 * original variable took less than 4 bytes

			 */

			t->size = 1;

			*(int *)(t+1) = BTF_INT_ENC(0, 0, 8);

		} else if (!has_datasec && kind == BTF_KIND_DATASEC) {

			/* replace DATASEC with STRUCT */

			struct btf_var_secinfo *v = (void *)(t + 1);