[PATCH bpf 0/1] Fix memory leak in helpers dealing with sockets

From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	Lorenz Bauer <lmb@cloudflare.com>,
	Martin KaFai Lau <kafai@fb.com>, Joe Stringer <joe@isovalent.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: kernel-team@cloudflare.com, edumazet@google.com
Subject: [PATCH bpf 0/1] Fix memory leak in helpers dealing with sockets
Date: Thu,  9 Jan 2020 11:57:47 +0000	[thread overview]
Message-ID: <20200109115749.12283-1-lmb@cloudflare.com> (raw)

While rolling out a new BPF based TC classifier I hit a memory leak, which
manifests in large numbers of request and time wait sockets not being released.

The root cause is that the current BPF helpers dealing with sockets are naive:
they assume that sk->sk_flags is always valid. struct request_sock and
struct inet_timewait_sock break this.

I've fixed this up by adding a helper that checks sk_state in addition to sk_flags.
The solution is a bit clumsy: it encapsulates details of struct sock in BPF.
It would probably be nicer to have a sock_gen_put + SOCK_RCU_FREE function exposed
in sock.h, but that might be too big a change for backports.

Thoughts?

Lorenz Bauer (1):
  net: bpf: don't leak time wait and request sockets

 net/core/filter.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

-- 
2.20.1