From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>
Cc: netdev@vger.kernel.org, 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>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach
Date: Mon, 11 Jan 2021 20:16:50 +0100 [thread overview]
Message-ID: <20210111191650.1241578-1-jolsa@kernel.org> (raw)
The bpf_tracing_prog_attach error path calls bpf_prog_put
on prog, which causes refcount underflow when it's called
from link_create function.
link_create
prog = bpf_prog_get <-- get
...
tracing_bpf_link_attach(prog..
bpf_tracing_prog_attach(prog..
out_put_prog:
bpf_prog_put(prog); <-- put
if (ret < 0)
bpf_prog_put(prog); <-- put
Removing bpf_prog_put call from bpf_tracing_prog_attach
and making sure its callers call it instead.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/bpf/syscall.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c3bb03c8371f..e5999d86c76e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2712,7 +2712,6 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
out_put_prog:
if (tgt_prog_fd && tgt_prog)
bpf_prog_put(tgt_prog);
- bpf_prog_put(prog);
return err;
}
@@ -2825,7 +2824,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
tp_name = prog->aux->attach_func_name;
break;
}
- return bpf_tracing_prog_attach(prog, 0, 0);
+ err = bpf_tracing_prog_attach(prog, 0, 0);
+ if (err >= 0)
+ return err;
+ goto out_put_prog;
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
if (strncpy_from_user(buf,
--
2.26.2
next reply other threads:[~2021-01-11 19:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 19:16 Jiri Olsa [this message]
2021-01-11 20:03 ` [PATCH] bpf: Prevent double bpf_prog_put call from bpf_tracing_prog_attach Toke Høiland-Jørgensen
2021-01-11 20:34 ` Andrii Nakryiko
2021-01-11 21:17 ` Jiri Olsa
2021-01-11 21:26 ` Andrii Nakryiko
2021-01-11 23:40 ` patchwork-bot+netdevbpf
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