On Wed, Oct 06, 2021 at 02:28 AM CEST, Kumar Kartikeya Dwivedi wrote:
> Similar to the fix in commit:
> e31eec77e4ab (bpf: selftests: Fix fd cleanup in get_branch_snapshot)
>
> We use memset to set fds to -1 without breaking on future changes to
> the array size (when MAX_SERVER constant is bumped).
>
> The particular close(0) occurs on non-reuseport tests, so it can be seen
> with -n 115/{2,3} but not 115/4. This can cause problems with future
> tests if they depend on BTF fd never being acquired as fd 0, breaking
> internal libbpf assumptions.
>
> Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> Fixes: 0ab5539f8584 (selftests/bpf: Tests for BPF_SK_LOOKUP attach point)
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
> ---
> .../selftests/bpf/prog_tests/sk_lookup.c | 20 +++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> index aee41547e7f4..572220065bdf 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> @@ -598,11 +598,14 @@ static void query_lookup_prog(struct test_sk_lookup *skel)
>
> static void run_lookup_prog(const struct test *t)
> {
> - int server_fds[MAX_SERVERS] = { -1 };
> int client_fd, reuse_conn_fd = -1;
> struct bpf_link *lookup_link;
> + int server_fds[MAX_SERVERS];
> int i, err;
>
> + /* set all fds to -1 */
> + memset(server_fds, 0xFF, sizeof(server_fds));
> +
> lookup_link = attach_lookup_prog(t->lookup_prog);
> if (!lookup_link)
> return;
> @@ -663,8 +666,9 @@ static void run_lookup_prog(const struct test *t)
> if (reuse_conn_fd != -1)
> close(reuse_conn_fd);
> for (i = 0; i < ARRAY_SIZE(server_fds); i++) {
> - if (server_fds[i] != -1)
> - close(server_fds[i]);
> + if (server_fds[i] == -1)
> + break;
> + close(server_fds[i]);
> }
> bpf_link__destroy(lookup_link);
> }
> @@ -1053,11 +1057,14 @@ static void run_sk_assign(struct test_sk_lookup *skel,
> struct bpf_program *lookup_prog,
> const char *remote_ip, const char *local_ip)
> {
> - int server_fds[MAX_SERVERS] = { -1 };
> + int server_fds[MAX_SERVERS];
> struct bpf_sk_lookup ctx;
> __u64 server_cookie;
> int i, err;
>
> + /* set all fds to -1 */
> + memset(server_fds, 0xFF, sizeof(server_fds));
> +
> DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
> .ctx_in = &ctx,
> .ctx_size_in = sizeof(ctx),
> @@ -1097,8 +1104,9 @@ static void run_sk_assign(struct test_sk_lookup *skel,
>
> close_servers:
> for (i = 0; i < ARRAY_SIZE(server_fds); i++) {
> - if (server_fds[i] != -1)
> - close(server_fds[i]);
> + if (server_fds[i] == -1)
> + break;
> + close(server_fds[i]);
> }
> }
My mistake. Thanks for the fix.
Alternatively we can use an extended designated initializer:
int server_fds[] = { [0 ... MAX_SERVERS] = -1 };
Reviewed-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
