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Thu, 27 Feb 2025 12:57:20 -0800 (PST) Received: from gmail.com ([98.97.44.1]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-223501d5247sm19775925ad.26.2025.02.27.12.57.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2025 12:57:19 -0800 (PST) Date: Thu, 27 Feb 2025 12:57:15 -0800 From: John Fastabend To: Cong Wang Cc: Jiayuan Chen , cong.wang@bytedance.com, jakub@cloudflare.com, 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, 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: Re: [PATCH bpf-next v1 1/3] bpf, sockmap: avoid using sk_socket after free Message-ID: <20250227205641.n2zpm5yetkoopvcz@gmail.com> References: <20250226132242.52663-1-jiayuan.chen@linux.dev> <20250226132242.52663-2-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 2025-02-27 11:45:53, Cong Wang wrote: > On Wed, Feb 26, 2025 at 09:22:40PM +0800, Jiayuan Chen wrote: > > 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 > > sock_def_readable() already acquires RCU read lock anyway. > > Reviewed-by: Cong Wang Thanks. Reviewed-by: John Fastabend