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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf-next 2/4] libbpf: ignore incompatible types with matching name during CO-RE relocation
Date: Fri, 13 Mar 2020 10:23:34 -0700	[thread overview]
Message-ID: <20200313172336.1879637-3-andriin@fb.com> (raw)
In-Reply-To: <20200313172336.1879637-1-andriin@fb.com>

When finding target type candidates, ignore forward declarations, functions,
and other named types of incompatible kind. Not doing this can cause false
errors.  See [0] for one such case (due to struct pt_regs forward

  [0] https://github.com/iovisor/bcc/pull/2806#issuecomment-598543645

Fixes: ddc7c3042614 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Reported-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
 tools/lib/bpf/libbpf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1a787a2faf58..085e41f9b68e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3873,6 +3873,10 @@ static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
 		if (str_is_empty(targ_name))
+		t = skip_mods_and_typedefs(targ_btf, i, NULL);
+		if (!btf_is_composite(t) && !btf_is_array(t))
+			continue;
 		targ_essent_len = bpf_core_essential_name_len(targ_name);
 		if (targ_essent_len != local_essent_len)

  parent reply	other threads:[~2020-03-13 17:24 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-13 17:23 [PATCH bpf-next 0/4] CO-RE candidate matching fix and tracing test Andrii Nakryiko
2020-03-13 17:23 ` [PATCH bpf-next 1/4] selftests/bpf: ensure consistent test failure output Andrii Nakryiko
2020-03-13 17:23 ` Andrii Nakryiko [this message]
2020-03-13 17:23 ` [PATCH bpf-next 3/4] libbpf: provide CO-RE variants of PT_REGS macros Andrii Nakryiko
2020-03-13 17:23 ` [PATCH bpf-next 4/4] selftests/bpf: add vmlinux.h selftest exercising tracing of syscalls Andrii Nakryiko
2020-03-13 17:47 ` [PATCH bpf-next 0/4] CO-RE candidate matching fix and tracing test Martin KaFai Lau
2020-03-13 22:36 ` Daniel Borkmann
  -- strict thread matches above, loose matches on Subject: below --
2020-03-13  7:54 Andrii Nakryiko
2020-03-13  7:54 ` [PATCH bpf-next 2/4] libbpf: ignore incompatible types with matching name during CO-RE relocation Andrii Nakryiko

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