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AJvYcCUWxdEW4AFfRt2yovqXurZwK5cPwIkiKMf4K0v1h5dOopPrWG8D59vkY5l0KckSOMI6ENGojKQtPesIc8gOP08MK5qO X-Gm-Message-State: AOJu0YzAiUrdVJyiWy9pnqqrR1kF0YrewK2hhapAJcLjAFC85eJRpBfs x71s/594iZbHZKcSCuyHmpCl0Hnu1m81pS99+lT9RYJQdeefFCNrwiAuQcYF X-Google-Smtp-Source: AGHT+IFgdeVyr6TLILVudglYWwR6UVYpd53NRGpzrYHcYE3RArhA8GcTaM3e9SiIEzFt/4tIfnQT4A== X-Received: by 2002:a17:90b:1905:b0:2a2:510f:fa4b with SMTP id mp5-20020a17090b190500b002a2510ffa4bmr351968pjb.10.1712292220186; Thu, 04 Apr 2024 21:43:40 -0700 (PDT) Received: from localhost ([98.97.36.54]) by smtp.gmail.com with ESMTPSA id p12-20020a17090b010c00b002a203bd94bfsm555131pjz.51.2024.04.04.21.43.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Apr 2024 21:43:39 -0700 (PDT) Date: Thu, 04 Apr 2024 21:43:38 -0700 From: John Fastabend To: Jason Xing , john.fastabend@gmail.com, edumazet@google.com, jakub@cloudflare.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, daniel@iogearbox.net, ast@kernel.org Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Jason Xing , syzbot+aa8c8ec2538929f18f2d@syzkaller.appspotmail.com Message-ID: <660f817ad9464_50b8720845@john.notmuch> In-Reply-To: <20240404021001.94815-1-kerneljasonxing@gmail.com> References: <20240404021001.94815-1-kerneljasonxing@gmail.com> Subject: RE: [PATCH net v2] bpf, skmsg: fix NULL pointer dereference in sk_psock_skb_ingress_enqueue Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Jason Xing wrote: > From: Jason Xing > > Fix NULL pointer data-races in sk_psock_skb_ingress_enqueue() which > syzbot reported [1]. > > [1] > BUG: KCSAN: data-race in sk_psock_drop / sk_psock_skb_ingress_enqueue > > write to 0xffff88814b3278b8 of 8 bytes by task 10724 on cpu 1: > sk_psock_stop_verdict net/core/skmsg.c:1257 [inline] > sk_psock_drop+0x13e/0x1f0 net/core/skmsg.c:843 > sk_psock_put include/linux/skmsg.h:459 [inline] > sock_map_close+0x1a7/0x260 net/core/sock_map.c:1648 > unix_release+0x4b/0x80 net/unix/af_unix.c:1048 > __sock_release net/socket.c:659 [inline] > sock_close+0x68/0x150 net/socket.c:1421 > __fput+0x2c1/0x660 fs/file_table.c:422 > __fput_sync+0x44/0x60 fs/file_table.c:507 > __do_sys_close fs/open.c:1556 [inline] > __se_sys_close+0x101/0x1b0 fs/open.c:1541 > __x64_sys_close+0x1f/0x30 fs/open.c:1541 > do_syscall_64+0xd3/0x1d0 > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > read to 0xffff88814b3278b8 of 8 bytes by task 10713 on cpu 0: > sk_psock_data_ready include/linux/skmsg.h:464 [inline] > sk_psock_skb_ingress_enqueue+0x32d/0x390 net/core/skmsg.c:555 > sk_psock_skb_ingress_self+0x185/0x1e0 net/core/skmsg.c:606 > sk_psock_verdict_apply net/core/skmsg.c:1008 [inline] > sk_psock_verdict_recv+0x3e4/0x4a0 net/core/skmsg.c:1202 > unix_read_skb net/unix/af_unix.c:2546 [inline] > unix_stream_read_skb+0x9e/0xf0 net/unix/af_unix.c:2682 > sk_psock_verdict_data_ready+0x77/0x220 net/core/skmsg.c:1223 > unix_stream_sendmsg+0x527/0x860 net/unix/af_unix.c:2339 > sock_sendmsg_nosec net/socket.c:730 [inline] > __sock_sendmsg+0x140/0x180 net/socket.c:745 > ____sys_sendmsg+0x312/0x410 net/socket.c:2584 > ___sys_sendmsg net/socket.c:2638 [inline] > __sys_sendmsg+0x1e9/0x280 net/socket.c:2667 > __do_sys_sendmsg net/socket.c:2676 [inline] > __se_sys_sendmsg net/socket.c:2674 [inline] > __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674 > do_syscall_64+0xd3/0x1d0 > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > value changed: 0xffffffff83d7feb0 -> 0x0000000000000000 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 0 PID: 10713 Comm: syz-executor.4 Tainted: G W 6.8.0-syzkaller-08951-gfe46a7dd189e #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 > > Prior to this, commit 4cd12c6065df ("bpf, sockmap: Fix NULL pointer > dereference in sk_psock_verdict_data_ready()") fixed one NULL pointer > similarly due to no protection of saved_data_ready. Here is another > different caller causing the same issue because of the same reason. So > we should protect it with sk_callback_lock read lock because the writer > side in the sk_psock_drop() uses "write_lock_bh(&sk->sk_callback_lock);". > > To avoid errors that could happen in future, I move those two pairs of > lock into the sk_psock_data_ready(), which is suggested by John Fastabend. > > Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") > Reported-by: syzbot+aa8c8ec2538929f18f2d@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=aa8c8ec2538929f18f2d > Signed-off-by: Jason Xing > --- > v2 > Link: https://lore.kernel.org/all/20240329134037.92124-1-kerneljasonxing@gmail.com/ > 1. move the read_lock_bh()/unlock_bh() into the sk_psock_data_ready() call (John) > Signed-off-by: Jason Xing > --- Reviewed-by: John Fastabend