selftests/bpf: Free per-cpu values array in bpf_iter selftest

mainline inclusion
from mainline-5.17-rc1
commit b8b26e58
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b8b26e585f3a0fbcee1032c622f046787da57390

-------------------------------------------------

Array holding per-cpu values wasn't freed. Fix that.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211107165521.9240-5-andrii@kernel.org
(cherry picked from commit b8b26e58)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/testing/selftests/bpf/prog_tests/bpf_iter.c

@@ -674,14 +674,13 @@ static void test_bpf_percpu_hash_map(void)
 	char buf[64];
 	void *val;
 
-	val = malloc(8 * bpf_num_possible_cpus());
-
 	skel = bpf_iter_bpf_percpu_hash_map__open();
 	if (CHECK(!skel, "bpf_iter_bpf_percpu_hash_map__open",
 		  "skeleton open failed\n"))
 		return;
 
 	skel->rodata->num_cpus = bpf_num_possible_cpus();
+	val = malloc(8 * bpf_num_possible_cpus());
 
 	err = bpf_iter_bpf_percpu_hash_map__load(skel);
 	if (CHECK(!skel, "bpf_iter_bpf_percpu_hash_map__load",
@@ -746,6 +745,7 @@ static void test_bpf_percpu_hash_map(void)
 	bpf_link__destroy(link);
 out:
 	bpf_iter_bpf_percpu_hash_map__destroy(skel);
+	free(val);
 }
 
 static void test_bpf_array_map(void)
@@ -846,14 +846,13 @@ static void test_bpf_percpu_array_map(void)
 	void *val;
 	int len;
 
-	val = malloc(8 * bpf_num_possible_cpus());
-
 	skel = bpf_iter_bpf_percpu_array_map__open();
 	if (CHECK(!skel, "bpf_iter_bpf_percpu_array_map__open",
 		  "skeleton open failed\n"))
 		return;
 
 	skel->rodata->num_cpus = bpf_num_possible_cpus();
+	val = malloc(8 * bpf_num_possible_cpus());
 
 	err = bpf_iter_bpf_percpu_array_map__load(skel);
 	if (CHECK(!skel, "bpf_iter_bpf_percpu_array_map__load",
@@ -909,6 +908,7 @@ static void test_bpf_percpu_array_map(void)
 	bpf_link__destroy(link);
 out:
 	bpf_iter_bpf_percpu_array_map__destroy(skel);
+	free(val);
 }
 
 static void test_bpf_sk_storage_map(void)