From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: bpf@vger.kernel.org
Cc: "Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
netdev@vger.kernel.org
Subject: [PATCH bpf-next v4 10/11] libbpf: Fix skel_internal.h to set errno on loader retval < 0
Date: Mon, 20 Sep 2021 19:45:25 +0530 [thread overview]
Message-ID: <20210920141526.3940002-11-memxor@gmail.com> (raw)
In-Reply-To: <20210920141526.3940002-1-memxor@gmail.com>
When the loader indicates an internal error (result of a checked bpf
system call), it returns the result in attr.test.retval. However, tests
that rely on ASSERT_OK_PTR on NULL (returned from light skeleton) may
miss that NULL denotes an error if errno is set to 0. This would result
in skel pointer being NULL, while ASSERT_OK_PTR returning 1, leading to
a SEGV on dereference of skel, because libbpf_get_error relies on the
assumption that errno is always set in case of error for ptr == NULL.
In particular, this was observed for the ksyms_module test. When
executed using `./test_progs -t ksyms`, prior tests manipulated errno
and the test didn't crash when it failed at ksyms_module load, while
using `./test_progs -t ksyms_module` crashed due to errno being
untouched.
Fixes: 67234743736a (libbpf: Generate loader program out of BPF ELF file.)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
tools/lib/bpf/skel_internal.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h
index 6c0f0adfd42f..c7eb88040d6b 100644
--- a/tools/lib/bpf/skel_internal.h
+++ b/tools/lib/bpf/skel_internal.h
@@ -116,10 +116,12 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
err = skel_sys_bpf(BPF_PROG_RUN, &attr, sizeof(attr));
if (err < 0 || (int)attr.test.retval < 0) {
opts->errstr = "failed to execute loader prog";
- if (err < 0)
+ if (err < 0) {
err = -errno;
- else
+ } else {
err = (int)attr.test.retval;
+ errno = -err;
+ }
goto out;
}
err = 0;
--
2.33.0
next prev parent reply other threads:[~2021-09-20 14:16 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 14:15 [PATCH bpf-next v4 00/11] Support kernel module function calls from eBPF Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 01/11] bpf: Introduce BPF support for kernel module function calls Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 02/11] bpf: Be conservative while processing invalid kfunc calls Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 03/11] bpf: btf: Introduce helpers for dynamic BTF set registration Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 04/11] tools: Allow specifying base BTF file in resolve_btfids Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 05/11] bpf: Enable TCP congestion control kfunc from modules Kumar Kartikeya Dwivedi
2021-09-21 22:18 ` Andrii Nakryiko
2021-09-21 22:23 ` Kumar Kartikeya Dwivedi
2021-09-21 23:02 ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 06/11] libbpf: Support kernel module function calls Kumar Kartikeya Dwivedi
2021-09-21 22:41 ` Andrii Nakryiko
2021-09-24 23:54 ` Kumar Kartikeya Dwivedi
2021-09-25 0:30 ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 07/11] libbpf: Resolve invalid weak kfunc calls with imm = 0, off = 0 Kumar Kartikeya Dwivedi
2021-09-21 22:47 ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 08/11] libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations Kumar Kartikeya Dwivedi
2021-09-21 0:57 ` Alexei Starovoitov
2021-09-21 4:50 ` Kumar Kartikeya Dwivedi
2021-09-21 19:04 ` Alexei Starovoitov
2021-09-21 22:25 ` Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 09/11] tools: bpftool: Add separate fd_array map support for light skeleton Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` Kumar Kartikeya Dwivedi [this message]
2021-09-20 14:15 ` [PATCH bpf-next v4 11/11] bpf: selftests: Add selftests for module kfunc support Kumar Kartikeya Dwivedi
2021-09-21 23:00 ` Andrii Nakryiko
2021-09-21 23:13 ` Kumar Kartikeya Dwivedi
2021-09-21 23:28 ` Kumar Kartikeya Dwivedi
2021-09-22 0:03 ` Andrii Nakryiko
2021-09-22 6:06 ` Kumar Kartikeya Dwivedi
2021-09-22 18:24 ` Alexei Starovoitov
2021-09-21 0:29 ` [PATCH bpf-next v4 00/11] Support kernel module function calls from eBPF Andrii Nakryiko
2021-09-21 4:55 ` Kumar Kartikeya Dwivedi
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