Re: [PATCH bpf-next] selftests/bpf: Sanitize pointer prior fclose()

On Tue, Mar 18, 2025 at 09:16:47AM +0100, Björn Töpel wrote:

From: Björn Töpel bjorn@rivosinc.com

There are scenarios where env.{sub,}test_state->stdout_saved, can be NULL, e.g. sometimes when the watchdog timeout kicks in, or if the open_memstream syscall is not available.

Avoid crashing test_progs by adding an explicit NULL check prior the fclose() call.

Signed-off-by: Björn Töpel bjorn@rivosinc.com

Acked-by: Jiri Olsa jolsa@kernel.org

jirka

---

tools/testing/selftests/bpf/test_progs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index d4ec9586b98c..309d9d4a8ace 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -103,12 +103,14 @@ static void stdio_restore(void) pthread_mutex_lock(&stdout_lock); if (env.subtest_state) {

• fclose(env.subtest_state->stdout_saved);
  

• if (env.subtest_state->stdout_saved)
  

• 	fclose(env.subtest_state->stdout_saved);
  

  env.subtest_state->stdout_saved = NULL;

nit, setting to NULL could be inside the condition

stdout = env.test_state->stdout_saved;
stderr = env.test_state->stdout_saved;

} else {

• fclose(env.test_state->stdout_saved);
  

• if (env.test_state->stdout_saved)
  

• 	fclose(env.test_state->stdout_saved);
  

  env.test_state->stdout_saved = NULL; stdout = env.stdout_saved; stderr = env.stderr_saved;

base-commit: f3f8649585a445414521a6d5b76f41b51205086d

2.45.2