On Tue, Jun 21, 2022 at 07:00 PM +02, Daniel Borkmann wrote: > On 6/21/22 9:01 AM, Jörn-Thorben Hinz wrote: >> test_sock_fields__detach() got called with a null pointer here when one >> of the CHECKs or ASSERTs up to the test_sock_fields__open_and_load() >> call resulted in a jump to the "done" label. >> A skeletons *__detach() is not safe to call with a null pointer, though. >> This led to a segfault. >> Go the easy route and only call test_sock_fields__destroy() which is >> null-pointer safe and includes detaching. >> Came across this while looking[1] to introduce the usage of >> bpf_tcp_helpers.h (included in progs/test_sock_fields.c) together with >> vmlinux.h. >> [1] >> https://lore.kernel.org/bpf/629bc069dd807d7ac646f836e9dca28bbc1108e2.camel@xxxxxxxxxxxxxxxxxxxx/ >> Fixes: 8f50f16ff39d ("selftests/bpf: Extend verifier and bpf_sock tests for >> dst_port loads") >> Signed-off-by: Jörn-Thorben Hinz <jthinz@xxxxxxxxxxxxxxxxxxxx> >> --- >> tools/testing/selftests/bpf/prog_tests/sock_fields.c | 1 - >> 1 file changed, 1 deletion(-) >> diff --git a/tools/testing/selftests/bpf/prog_tests/sock_fields.c >> b/tools/testing/selftests/bpf/prog_tests/sock_fields.c >> index 9d211b5c22c4..7d23166c77af 100644 >> --- a/tools/testing/selftests/bpf/prog_tests/sock_fields.c >> +++ b/tools/testing/selftests/bpf/prog_tests/sock_fields.c >> @@ -394,7 +394,6 @@ void serial_test_sock_fields(void) >> test(); >> done: >> - test_sock_fields__detach(skel); >> test_sock_fields__destroy(skel); >> if (child_cg_fd >= 0) >> close(child_cg_fd); >> > > Great catch! I think we have similar detach & destroy pattern in a number > of places in selftests. > > Should we rather just move the label, like: > > diff --git a/tools/testing/selftests/bpf/prog_tests/sock_fields.c b/tools/testing/selftests/bpf/prog_tests/sock_fields.c > index 9d211b5c22c4..e8a947241e37 100644 > --- a/tools/testing/selftests/bpf/prog_tests/sock_fields.c > +++ b/tools/testing/selftests/bpf/prog_tests/sock_fields.c > @@ -393,8 +393,8 @@ void serial_test_sock_fields(void) > > test(); > > -done: > test_sock_fields__detach(skel); > +done: > test_sock_fields__destroy(skel); > if (child_cg_fd >= 0) > close(child_cg_fd); *__destroy() will call bpf_object__detach_skeleton(), so it LGTM. Thanks for the fix. Reviewed-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
