Commit b23ed4d7 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Daniel Borkmann
Browse files

selftests/bpf: Fix invalid pointer check in get_xlated_program() 



Dan Carpenter reported invalid check for calloc() result in
test_verifier.c:get_xlated_program():

  ./tools/testing/selftests/bpf/test_verifier.c:1365 get_xlated_program()
  warn: variable dereferenced before check 'buf' (see line 1364)

  ./tools/testing/selftests/bpf/test_verifier.c
    1363		*cnt = xlated_prog_len / buf_element_size;
    1364		*buf = calloc(*cnt, buf_element_size);
    1365		if (!buf) {

  This should be if (!*buf) {

    1366			perror("can't allocate xlated program buffer");
    1367			return -ENOMEM;

This commit refactors the get_xlated_program() to avoid using double
pointer type.

Fixes: 933ff531 ("selftests/bpf: specify expected instructions in test_verifier tests")
Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/ZH7u0hEGVB4MjGZq@moroto/
Link: https://lore.kernel.org/bpf/20230609221637.2631800-1-eddyz87@gmail.com
parent 67faabbd

tools/testing/selftests/bpf/test_verifier.c

+13 −11
Original line number Diff line number Diff line
@@ -1341,45 +1341,46 @@ static bool cmp_str_seq(const char *log, const char *exp) 
	return true;

}



static int get_xlated_program(int fd_prog, struct bpf_insn **buf, int *cnt)

static struct bpf_insn *get_xlated_program(int fd_prog, int *cnt)

{

	__u32 buf_element_size = sizeof(struct bpf_insn);

	struct bpf_prog_info info = {};

	__u32 info_len = sizeof(info);

	__u32 xlated_prog_len;

	__u32 buf_element_size = sizeof(struct bpf_insn);

	struct bpf_insn *buf;



	if (bpf_prog_get_info_by_fd(fd_prog, &info, &info_len)) {

		perror("bpf_prog_get_info_by_fd failed");

		return -1;

		return NULL;

	}



	xlated_prog_len = info.xlated_prog_len;

	if (xlated_prog_len % buf_element_size) {

		printf("Program length %d is not multiple of %d\n",

		       xlated_prog_len, buf_element_size);

		return -1;

		return NULL;

	}



	*cnt = xlated_prog_len / buf_element_size;

	*buf = calloc(*cnt, buf_element_size);

	buf = calloc(*cnt, buf_element_size);

	if (!buf) {

		perror("can't allocate xlated program buffer");

		return -ENOMEM;

		return NULL;

	}



	bzero(&info, sizeof(info));

	info.xlated_prog_len = xlated_prog_len;

	info.xlated_prog_insns = (__u64)(unsigned long)*buf;

	info.xlated_prog_insns = (__u64)(unsigned long)buf;

	if (bpf_prog_get_info_by_fd(fd_prog, &info, &info_len)) {

		perror("second bpf_prog_get_info_by_fd failed");

		goto out_free_buf;

	}



	return 0;

	return buf;



out_free_buf:

	free(*buf);

	return -1;

	free(buf);

	return NULL;

}



static bool is_null_insn(struct bpf_insn *insn)
@@ -1512,7 +1513,8 @@ static bool check_xlated_program(struct bpf_test *test, int fd_prog) 
	if (!check_expected && !check_unexpected)

		goto out;



	if (get_xlated_program(fd_prog, &buf, &cnt)) {

	buf = get_xlated_program(fd_prog, &cnt);

	if (!buf) {

		printf("FAIL: can't get xlated program\n");

		result = false;

		goto out;