selftests/bpf: Add malloc failure checks in bpf_iter

Since some malloc calls in bpf_iter may at times fail,
this patch adds the appropriate fail checks, and ensures that
any previously allocated resource is appropriately destroyed
before returning the function.

Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/DB3PR10MB6835F0ECA792265FA41FC39BE8A3A@DB3PR10MB6835.EURPRD10.PROD.OUTLOOK.COM
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: yuranpereira

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

@@ -698,7 +698,7 @@ static void test_overflow(bool test_e2big_overflow, bool ret1)
 		goto free_link;
 
 	buf = malloc(expected_read_len);
-	if (!buf)
+	if (!ASSERT_OK_PTR(buf, "malloc"))
 		goto close_iter;
 
 	/* do read */
@@ -868,6 +868,8 @@ static void test_bpf_percpu_hash_map(void)
 
 	skel->rodata->num_cpus = bpf_num_possible_cpus();
 	val = malloc(8 * bpf_num_possible_cpus());
+	if (!ASSERT_OK_PTR(val, "malloc"))
+		goto out;
 
 	err = bpf_iter_bpf_percpu_hash_map__load(skel);
 	if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_percpu_hash_map__load"))
@@ -1044,6 +1046,8 @@ static void test_bpf_percpu_array_map(void)
 
 	skel->rodata->num_cpus = bpf_num_possible_cpus();
 	val = malloc(8 * bpf_num_possible_cpus());
+	if (!ASSERT_OK_PTR(val, "malloc"))
+		goto out;
 
 	err = bpf_iter_bpf_percpu_array_map__load(skel);
 	if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_percpu_array_map__load"))