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[203.218.154.232]) by smtp.gmail.com with ESMTPSA id t10-20020a65554a000000b004126f1e48f4sm685439pgr.20.2022.07.09.01.36.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 Jul 2022 01:37:03 -0700 (PDT) From: Hawkins Jiawei To: kuba@kernel.org Cc: 18801353760@163.com, andrii@kernel.org, ast@kernel.org, borisp@nvidia.com, bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, guwen@linux.alibaba.com, john.fastabend@gmail.com, kafai@fb.com, kgraul@linux.ibm.com, kpsingh@kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, paskripkin@gmail.com, skhan@linuxfoundation.org, songliubraving@fb.com, syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, yhs@fb.com, yin31149@gmail.com, yoshfuji@linux-ipv6.org Subject: Re: [PATCH] smc: fix refcount bug in sk_psock_get (2) Date: Sat, 9 Jul 2022 16:36:42 +0800 Message-Id: <20220709083641.2060-1-yin31149@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220708200602.1059bc09@kernel.org> References: <20220708200602.1059bc09@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Sat, 9 Jul 2022 at 11:06, Jakub Kicinski wrote: > On Sat, 9 Jul 2022 10:46:59 +0800 Hawkins Jiawei wrote: > > Reported-and-tested-by: syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com > > Signed-off-by: hawk <18801353760@163.com> > > --- > > net/ipv4/tcp.c | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > > index 9984d23a7f3e..a1e6cab2c748 100644 > > --- a/net/ipv4/tcp.c > > +++ b/net/ipv4/tcp.c > > @@ -3395,10 +3395,23 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname, > > } > > case TCP_ULP: { > > char name[TCP_ULP_NAME_MAX]; > > + struct sock *smc_sock; > > > > if (optlen < 1) > > return -EINVAL; > > > > + /* SMC sk_user_data may be treated as psock, > > + * which triggers a refcnt warning. > > + */ > > + rcu_read_lock(); > > + smc_sock = rcu_dereference_sk_user_data(sk); > > + if (level == SOL_TCP && smc_sock && > > + smc_sock->__sk_common.skc_family == AF_SMC) { > > This should prolly be under the socket lock? > > Can we add a bit to SK_USER_DATA_PTRMASK and have ULP-compatible > users (sockmap) opt into ULP cooperation? Modifying TCP is backwards, > layer-wise. Thanks for your suggestion, I also agree that modifying TCP directly is not wise. I am sorry that I can't follow you on haveing ULP-compatible users (sockmap) opt into ULP cooperation, yet adding a bit to SK_USER_DATA_PTRMASK seems like a good way. I plan to add a mask bit, and check it during sk_psock_get(), in v2 patch > > > + rcu_read_unlock(); > > + return -EOPNOTSUPP; > > + } > > + rcu_read_unlock(); > > +