• Paolo Abeni's avatar
    mptcp: do not queue data on closed subflows · c886d702
    Paolo Abeni authored
    Dipanjan reported a syzbot splat at close time:
    
    WARNING: CPU: 1 PID: 10818 at net/ipv4/af_inet.c:153
    inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
    Modules linked in: uio_ivshmem(OE) uio(E)
    CPU: 1 PID: 10818 Comm: kworker/1:16 Tainted: G           OE
    5.19.0-rc6-g2eae0556bb9d #2
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
    1.13.0-1ubuntu1.1 04/01/2014
    Workqueue: events mptcp_worker
    RIP: 0010:inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
    Code: 21 02 00 00 41 8b 9c 24 28 02 00 00 e9 07 ff ff ff e8 34 4d 91
    f9 89 ee 4c 89 e7 e8 4a 47 60 ff e9 a6 fc ff ff e8 20 4d 91 f9 <0f> 0b
    e9 84 fe ff ff e8 14 4d 91 f9 0f 0b e9 d4 fd ff ff e8 08 4d
    RSP: 0018:ffffc9001b35fa78 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 00000000002879d0 RCX: ffff8881326f3b00
    RDX: 0000000000000000 RSI: ffff8881326f3b00 RDI: 0000000000000002
    RBP: ffff888179662674 R08: ffffffff87e983a0 R09: 0000000000000000
    R10: 0000000000000005 R11: 00000000000004ea R12: ffff888179662400
    R13: ffff888179662428 R14: 0000000000000001 R15: ffff88817e38e258
    FS:  0000000000000000(0000) GS:ffff8881f5f00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000020007bc0 CR3: 0000000179592000 CR4: 0000000000150ee0
    Call Trace:
     <TASK>
     __sk_destruct+0x4f/0x8e0 net/core/sock.c:2067
     sk_destruct+0xbd/0xe0 net/core/sock.c:2112
     __sk_free+0xef/0x3d0 net/core/sock.c:2123
     sk_free+0x78/0xa0 net/core/sock.c:2134
     sock_put include/net/sock.h:1927 [inline]
     __mptcp_close_ssk+0x50f/0x780 net/mptcp/protocol.c:2351
     __mptcp_destroy_sock+0x332/0x760 net/mptcp/protocol.c:2828
     mptcp_worker+0x5d2/0xc90 net/mptcp/protocol.c:2586
     process_one_work+0x9cc/0x1650 kernel/workqueue.c:2289
     worker_thread+0x623/0x1070 kernel/workqueue.c:2436
     kthread+0x2e9/0x3a0 kernel/kthread.c:376
     ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
     </TASK>
    
    The root cause of the problem is that an mptcp-level (re)transmit can
    race with mptcp_close() and the packet scheduler checks the subflow
    state before acquiring the socket lock: we can try to (re)transmit on
    an already closed ssk.
    
    Fix the issue checking again the subflow socket status under the
    subflow socket lock protection. Additionally add the missing check
    for the fallback-to-tcp case.
    
    Fixes: d5f49190 ("mptcp: allow picking different xmit subflows")
    Reported-by: default avatarDipanjan Das <mail.dipanjan.das@gmail.com>
    Reviewed-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
    Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
    Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    c886d702
protocol.h 30.1 KB