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From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: [PATCH bpf] bpf: Force kprobe multi expected_attach_type for kprobe_multi link
Date: Tue, 13 Jun 2023 13:31:19 +0200	[thread overview]
Message-ID: <20230613113119.2348619-1-jolsa@kernel.org> (raw)

We currently allow to create perf link for program with
expected_attach_type == BPF_TRACE_KPROBE_MULTI.

This will cause crash when we call helpers like get_attach_cookie or
get_func_ip in such program, because it will call the kprobe_multi's
version (current->bpf_ctx context setup) of those helpers while it
expects perf_link's current->bpf_ctx context setup.

Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
only for programs attaching through kprobe_multi link.

Fixes: ca74823c6e16 ("bpf: Add cookie support to programs attached with kprobe multi link")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/syscall.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0c21d0d8efe4..e8fe04a5db93 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4675,6 +4675,11 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
 		ret = bpf_perf_link_attach(attr, prog);
 		break;
 	case BPF_PROG_TYPE_KPROBE:
+		if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
+		    attr->link_create.attach_type != BPF_TRACE_KPROBE_MULTI) {
+			ret = -EINVAL;
+			goto out;
+		}
 		if (attr->link_create.attach_type == BPF_PERF_EVENT)
 			ret = bpf_perf_link_attach(attr, prog);
 		else
-- 
2.40.1


             reply	other threads:[~2023-06-13 11:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-13 11:31 Jiri Olsa [this message]
2023-06-13 14:35 ` [PATCH bpf] bpf: Force kprobe multi expected_attach_type for kprobe_multi link Yonghong Song
2023-06-16 16:53 ` Andrii Nakryiko
2023-06-17 19:16   ` Jiri Olsa

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