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

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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: 933ff53191 ("selftests/bpf: specify expected instructions in test_verifier tests")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/ZH7u0hEGVB4MjGZq@moroto/
Link: https://lore.kernel.org/bpf/20230609221637.2631800-1-eddyz87@gmail.com
This commit is contained in:
Eduard Zingerman 2023-06-10 01:16:37 +03:00 committed by Daniel Borkmann
parent 67faabbde3
commit b23ed4d74c
1 changed files with 13 additions and 11 deletions
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24
tools/testing/selftests/bpf/test_verifier.c
View file

@ -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;