From patchwork Wed Feb 26 13:22:40 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiayuan Chen X-Patchwork-Id: 13992383 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C3858218ABB for ; Wed, 26 Feb 2025 13:23:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.186 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740576200; cv=none; b=ZvaWvfpT+sF2XIPzTfD9I66pFad0IhWwucK+CqdlEpU1zmO2P6RNz68hD6cUxVYqV0rK2C0SDiYLPxHi3k1o5uuEQQNHS6f143/r8OC78SwMmBa7MQamaeFT/bm9LpEc8RXNxAso9PMDqbeIm/2IFemQKRxkJ2Q+WZS7PbyqBPQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740576200; c=relaxed/simple; bh=DxPWP8rrv4ONenG/F6SsO3l4pfuop1FPheHU8L80WlE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p65063HmsOf9Wy/t8hVE4s4hHJc1wy/avbQ94S0phFtyuMXZ7JRF6WzJjTl6qDZw2X3brQCzhjRRxO+XHOiCOYMB8Zh65yHjvzUpR851HH0z6cJdt87Wy+Xo810pIfCnX1z0xGqYiliG6rUNnd5680/Tjrvg5ldX8GuK4CszAXI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=mV9OhvO4; arc=none smtp.client-ip=91.218.175.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="mV9OhvO4" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1740576195; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sz9Qjoc4T3rOFnOy9pSBe7N5DwMb8DWcqD7jnhchAio=; b=mV9OhvO46Jn4Y10khTwmaVDDqE9IPSMjc8H05+YyNGaUk/mvD8zERXwvGf0AWsEu0M9XJ/ TrulscdG7HjTAW8vcTffVqW7P8yT2iJioRzw/Gej4EhoHRIcWeMNt9zTxF8Rp2cq/ubtXF EvYYoLy4Q192+yi3s0IjylKHJUm5QIE= From: Jiayuan Chen To: cong.wang@bytedance.com, john.fastabend@gmail.com, jakub@cloudflare.com Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, andrii@kernel.org, eddyz87@gmail.com, mykolal@fb.com, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, shuah@kernel.org, mhal@rbox.co, jiayuan.chen@linux.dev, sgarzare@redhat.com, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, mrpre@163.com, syzbot+dd90a702f518e0eac072@syzkaller.appspotmail.com Subject: [PATCH bpf-next v1 1/3] bpf, sockmap: avoid using sk_socket after free Date: Wed, 26 Feb 2025 21:22:40 +0800 Message-ID: <20250226132242.52663-2-jiayuan.chen@linux.dev> In-Reply-To: <20250226132242.52663-1-jiayuan.chen@linux.dev> References: <20250226132242.52663-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net Use RCU lock to protect sk_socket, preventing concurrent close and release by another thread. Because TCP/UDP are already within a relatively large critical section: ''' ip_local_deliver_finish rcu_read_lock ip_protocol_deliver_rcu tcp_rcv/udp_rcv rcu_read_unlock ''' Adding rcu_read_{un}lock() at the entrance and exit of sk_data_ready will not increase performance overhead. Reported-by: syzbot+dd90a702f518e0eac072@syzkaller.appspotmail.com Closes: https://lore.kernel.org/bpf/6734c033.050a0220.2a2fcc.0015.GAE@google.com/ Signed-off-by: Jiayuan Chen --- net/core/skmsg.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 0ddc4c718833..1b71ae1d1bf5 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1222,27 +1222,35 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb) static void sk_psock_verdict_data_ready(struct sock *sk) { - struct socket *sock = sk->sk_socket; + struct socket *sock; const struct proto_ops *ops; int copied; trace_sk_data_ready(sk); + /* We need RCU to prevent the sk_socket from being released. + * Especially for Unix sockets, we are currently in the process + * context and do not have RCU protection. + */ + rcu_read_lock(); + sock = sk->sk_socket; if (unlikely(!sock)) - return; + goto unlock; + ops = READ_ONCE(sock->ops); if (!ops || !ops->read_skb) - return; + goto unlock; + copied = ops->read_skb(sk, sk_psock_verdict_recv); if (copied >= 0) { struct sk_psock *psock; - rcu_read_lock(); psock = sk_psock(sk); if (psock) sk_psock_data_ready(sk, psock); - rcu_read_unlock(); } +unlock: + rcu_read_unlock(); } void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock)