• E
    tcp: purge write queue in tcp_connect_init() · 7f582b24
    Eric Dumazet 提交于
    syzkaller found a reliable way to crash the host, hitting a BUG()
    in __tcp_retransmit_skb()
    
    Malicous MSG_FASTOPEN is the root cause. We need to purge write queue
    in tcp_connect_init() at the point we init snd_una/write_seq.
    
    This patch also replaces the BUG() by a less intrusive WARN_ON_ONCE()
    
    kernel BUG at net/ipv4/tcp_output.c:2837!
    invalid opcode: 0000 [#1] SMP KASAN
    Dumping ftrace buffer:
       (ftrace buffer empty)
    Modules linked in:
    CPU: 0 PID: 5276 Comm: syz-executor0 Not tainted 4.17.0-rc3+ #51
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    RIP: 0010:__tcp_retransmit_skb+0x2992/0x2eb0 net/ipv4/tcp_output.c:2837
    RSP: 0000:ffff8801dae06ff8 EFLAGS: 00010206
    RAX: ffff8801b9fe61c0 RBX: 00000000ffc18a16 RCX: ffffffff864e1a49
    RDX: 0000000000000100 RSI: ffffffff864e2e12 RDI: 0000000000000005
    RBP: ffff8801dae073a0 R08: ffff8801b9fe61c0 R09: ffffed0039c40dd2
    R10: ffffed0039c40dd2 R11: ffff8801ce206e93 R12: 00000000421eeaad
    R13: ffff8801ce206d4e R14: ffff8801ce206cc0 R15: ffff8801cd4f4a80
    FS:  0000000000000000(0000) GS:ffff8801dae00000(0063) knlGS:00000000096bc900
    CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
    CR2: 0000000020000000 CR3: 00000001c47b6000 CR4: 00000000001406f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     <IRQ>
     tcp_retransmit_skb+0x2e/0x250 net/ipv4/tcp_output.c:2923
     tcp_retransmit_timer+0xc50/0x3060 net/ipv4/tcp_timer.c:488
     tcp_write_timer_handler+0x339/0x960 net/ipv4/tcp_timer.c:573
     tcp_write_timer+0x111/0x1d0 net/ipv4/tcp_timer.c:593
     call_timer_fn+0x230/0x940 kernel/time/timer.c:1326
     expire_timers kernel/time/timer.c:1363 [inline]
     __run_timers+0x79e/0xc50 kernel/time/timer.c:1666
     run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
     __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285
     invoke_softirq kernel/softirq.c:365 [inline]
     irq_exit+0x1d1/0x200 kernel/softirq.c:405
     exiting_irq arch/x86/include/asm/apic.h:525 [inline]
     smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052
     apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
    
    Fixes: cf60af03 ("net-tcp: Fast Open client - sendmsg(MSG_FASTOPEN)")
    Signed-off-by: NEric Dumazet <edumazet@google.com>
    Cc: Yuchung Cheng <ycheng@google.com>
    Cc: Neal Cardwell <ncardwell@google.com>
    Reported-by: Nsyzbot <syzkaller@googlegroups.com>
    Acked-by: NNeal Cardwell <ncardwell@google.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    7f582b24
tcp_output.c 107.9 KB