libbpf: Fix cleanup on invalid CO-RE relocation offsets

bpf_object__relocate_core() allocates a CO-RE candidate cache before
processing relocation records. Two instruction offset validation
failures return -EINVAL directly instead of going through the common
cleanup path.

These checks were moved into bpf_object__relocate_core() when
bpf_core_apply_relo() was split, preserving direct returns that were
safe in the previous helper but now bypass cleanup.

Route both failures through the out path so the candidate cache and
target BTF override are released.

Signed-off-by: Luis Vieira <luisflavieira@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260929-libbpf-core-relo-cleanup-v1-1-c9cd0b5775a9@gmail.com

src/libbpf.c

@@ -6255,8 +6255,11 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 		pr_debug("sec '%s': found %u CO-RE relocations\n", sec_name, sec->num_info);
 
 		for_each_btf_ext_rec(seg, sec, i, rec) {
-			if (rec->insn_off % BPF_INSN_SZ)
-				return -EINVAL;
+			if (rec->insn_off % BPF_INSN_SZ) {
+				err = -EINVAL;
+				goto out;
+			}
+
 			insn_idx = rec->insn_off / BPF_INSN_SZ;
 			prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
 			if (!prog) {
@@ -6283,8 +6286,10 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 			 * relocated, so it's enough to just subtract in-section offset
 			 */
 			insn_idx = insn_idx - prog->sec_insn_off;
-			if (insn_idx >= prog->insns_cnt)
-				return -EINVAL;
+			if (insn_idx >= prog->insns_cnt) {
+				err = -EINVAL;
+				goto out;
+			}
 			insn = &prog->insns[insn_idx];
 
 			if (is_ldimm64_insn(insn) && (size_t)insn_idx + 1 >= prog->insns_cnt) {