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BC=-1|-1; BR=01201311R131e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=ay29a033018046051; MF=guwen@linux.alibaba.com; NM=1; PH=DS; RN=25; SR=0; TI=SMTPD_---0VLGi36p_1659526024; Received: from 30.227.65.209(mailfrom:guwen@linux.alibaba.com fp:SMTPD_---0VLGi36p_1659526024) by smtp.aliyun-inc.com; Wed, 03 Aug 2022 19:27:06 +0800 Message-ID: Date: Wed, 3 Aug 2022 19:27:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v3] net/smc: fix refcount bug in sk_psock_get (2) To: Hawkins Jiawei , syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com References: <00000000000026328205e08cdbeb@google.com> <20220803080338.166730-1-yin31149@gmail.com> From: Wen Gu In-Reply-To: <20220803080338.166730-1-yin31149@gmail.com> Cc: songliubraving@fb.com, ast@kernel.org, edumazet@google.com, jakub@cloudflare.com, daniel@iogearbox.net, davem@davemloft.net, borisp@nvidia.com, paskripkin@gmail.com, john.fastabend@gmail.com, andrii@kernel.org, yhs@fb.com, pabeni@redhat.com, linux-kernel-mentees@lists.linuxfoundation.org, syzkaller-bugs@googlegroups.com, kpsingh@kernel.org, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kgraul@linux.ibm.com, bpf@vger.kernel.org, kafai@fb.com X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" On 2022/8/3 16:03, Hawkins Jiawei wrote: > Syzkaller reports refcount bug as follows: > ------------[ cut here ]------------ > refcount_t: saturated; leaking memory. > WARNING: CPU: 1 PID: 3605 at lib/refcount.c:19 refcount_warn_saturate+0xf4/0x1e0 lib/refcount.c:19 > Modules linked in: > CPU: 1 PID: 3605 Comm: syz-executor208 Not tainted 5.18.0-syzkaller-03023-g7e062cda7d90 #0 > > __refcount_add_not_zero include/linux/refcount.h:163 [inline] > __refcount_inc_not_zero include/linux/refcount.h:227 [inline] > refcount_inc_not_zero include/linux/refcount.h:245 [inline] > sk_psock_get+0x3bc/0x410 include/linux/skmsg.h:439 > tls_data_ready+0x6d/0x1b0 net/tls/tls_sw.c:2091 > tcp_data_ready+0x106/0x520 net/ipv4/tcp_input.c:4983 > tcp_data_queue+0x25f2/0x4c90 net/ipv4/tcp_input.c:5057 > tcp_rcv_state_process+0x1774/0x4e80 net/ipv4/tcp_input.c:6659 > tcp_v4_do_rcv+0x339/0x980 net/ipv4/tcp_ipv4.c:1682 > sk_backlog_rcv include/net/sock.h:1061 [inline] > __release_sock+0x134/0x3b0 net/core/sock.c:2849 > release_sock+0x54/0x1b0 net/core/sock.c:3404 > inet_shutdown+0x1e0/0x430 net/ipv4/af_inet.c:909 > __sys_shutdown_sock net/socket.c:2331 [inline] > __sys_shutdown_sock net/socket.c:2325 [inline] > __sys_shutdown+0xf1/0x1b0 net/socket.c:2343 > __do_sys_shutdown net/socket.c:2351 [inline] > __se_sys_shutdown net/socket.c:2349 [inline] > __x64_sys_shutdown+0x50/0x70 net/socket.c:2349 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > > During SMC fallback process in connect syscall, kernel will > replaces TCP with SMC. In order to forward wakeup > smc socket waitqueue after fallback, kernel will sets > clcsk->sk_user_data to origin smc socket in > smc_fback_replace_callbacks(). > > Later, in shutdown syscall, kernel will calls > sk_psock_get(), which treats the clcsk->sk_user_data > as psock type, triggering the refcnt warning. > > So, the root cause is that smc and psock, both will use > sk_user_data field. So they will mismatch this field > easily. > > This patch solves it by using another bit(defined as > SK_USER_DATA_PSOCK) in PTRMASK, to mark whether > sk_user_data points to a psock object or not. > This patch depends on a PTRMASK introduced in commit f1ff5ce2cd5e > ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). > > Reported-and-tested-by: syzbot+5f26f85569bd179c18ce@syzkaller.appspotmail.com > Suggested-by: Jakub Kicinski > Acked-by: Wen Gu > Signed-off-by: Hawkins Jiawei > --- > v2 -> v3: > - use SK_USER_DATA_PSOCK instead of SK_USER_DATA_NOTPSOCK > to patch the bug > - refactor the code on assigning to sk_user_data field > in psock part > - refactor the code on getting and setting the flag > with sk_user_data field > > v1 -> v2: > - add bit in PTRMASK to patch the bug > > include/linux/skmsg.h | 2 +- > include/net/sock.h | 58 +++++++++++++++++++++++++++++++------------ > net/core/skmsg.c | 3 ++- > 3 files changed, 45 insertions(+), 18 deletions(-) > Hi Hawkins, Since the fix v3 doesn't involved smc codes any more, I wonder if it's still appropriate to use 'net/smc:' in subject? Cheers, Wen Gu _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees