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Tue, 21 Jun 2022 12:54:35 -0700 (PDT) Received: from localhost ([172.243.153.43]) by smtp.gmail.com with ESMTPSA id l4-20020a6b3e04000000b0066cc83ee8c2sm7963314ioa.48.2022.06.21.12.54.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jun 2022 12:54:34 -0700 (PDT) Date: Tue, 21 Jun 2022 12:54:27 -0700 From: John Fastabend To: =?UTF-8?B?SsO2cm4tVGhvcmJlbiBIaW56?= , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Jakub Sitnicki , =?UTF-8?B?SsO2cm4tVGhvcmJlbiBIaW56?= Message-ID: <62b221f3886d0_16274208b@john.notmuch> In-Reply-To: <20220621070116.307221-1-jthinz@mailbox.tu-berlin.de> References: <20220621070116.307221-1-jthinz@mailbox.tu-berlin.de> Subject: RE: [PATCH bpf-next] selftests/bpf: Fix rare segfault in sock_fields prog test Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org J=C3=B6rn-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/629bc069dd807d7ac646f836e9dca28bbc1108e= 2.camel@mailbox.tu-berlin.de/ > = > Fixes: 8f50f16ff39d ("selftests/bpf: Extend verifier and bpf_sock tests= for dst_port loads") > Signed-off-by: J=C3=B6rn-Thorben Hinz > --- > 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/too= ls/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 >=3D 0) > close(child_cg_fd); > -- = > 2.30.2 > = But we should still call __detach(skel) after the !skel check is done I assume. So rather than remove it should add a new label and jump to that, = done: test_sock_fields__detach(); done_no_skel: test_sock_fields__destroy()=