Linux/Unix 主機上安裝了一個或多個受到弱點影響的套件，且供應商未提供可用的修補程式。

  - 已解決 Linux 核心中的下列弱點：can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate The conclusion j1939_session_deactivate() should be called with a session ref-count of at least 2 is incorrect. In some concurrent scenarios, j1939_session_deactivate can be called with the session ref-count less than 2. But there is not any problem because it will check the session active state before session putting in j1939_session_deactivate_locked(). Here is the concurrent scenario of the problem reported by syzbot and my reproduction log. cpu0 cpu1 j1939_xtp_rx_eoma j1939_xtp_rx_abort_one j1939_session_get_by_addr [kref == 2] j1939_session_get_by_addr [kref == 3] j1939_session_deactivate [kref == 2] j1939_session_put [kref == 1] j1939_session_completed j1939_session_deactivate WARN_ON_ONCE(kref < 2) ===================================================== WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70 CPU: 1 PID:
    21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 RIP: 0010:j1939_session_deactivate+0x5f/0x70 Call Trace:
    j1939_session_deactivate_activate_next+0x11/0x28 j1939_xtp_rx_eoma+0x12a/0x180 j1939_tp_recv+0x4a2/0x510 j1939_can_recv+0x226/0x380 can_rcv_filter+0xf8/0x220 can_receive+0x102/0x220 ? process_backlog+0xf0/0x2c0 can_rcv+0x53/0xf0 __netif_receive_skb_one_core+0x67/0x90 ? process_backlog+0x97/0x2c0
    __netif_receive_skb+0x22/0x80 (CVE-2021-4454)

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偵測

Linux Distros 未修補的弱點：CVE-2021-4454

medium Nessus Plugin ID 247475

版本 1.17