• Eric Dumazet's avatar
    dccp: fix tasklet usage · a8d7aa17
    Eric Dumazet authored
    syzbot reported a crash in tasklet_action_common() caused by dccp.
    
    dccp needs to make sure socket wont disappear before tasklet handler
    has completed.
    
    This patch takes a reference on the socket when arming the tasklet,
    and moves the sock_put() from dccp_write_xmit_timer() to dccp_write_xmitlet()
    
    kernel BUG at kernel/softirq.c:514!
    invalid opcode: 0000 [#1] SMP KASAN
    Dumping ftrace buffer:
       (ftrace buffer empty)
    Modules linked in:
    CPU: 1 PID: 17 Comm: ksoftirqd/1 Not tainted 4.17.0-rc3+ #30
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    RIP: 0010:tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515
    RSP: 0018:ffff8801d9b3faf8 EFLAGS: 00010246
    dccp_close: ABORT with 65423 bytes unread
    RAX: 1ffff1003b367f6b RBX: ffff8801daf1f3f0 RCX: 0000000000000000
    RDX: ffff8801cf895498 RSI: 0000000000000004 RDI: 0000000000000000
    RBP: ffff8801d9b3fc40 R08: ffffed0039f12a95 R09: ffffed0039f12a94
    dccp_close: ABORT with 65423 bytes unread
    R10: ffffed0039f12a94 R11: ffff8801cf8954a3 R12: 0000000000000000
    R13: ffff8801d9b3fc18 R14: dffffc0000000000 R15: ffff8801cf895490
    FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000001b2bc28000 CR3: 00000001a08a9000 CR4: 00000000001406e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     tasklet_action+0x1d/0x20 kernel/softirq.c:533
     __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285
    dccp_close: ABORT with 65423 bytes unread
     run_ksoftirqd+0x86/0x100 kernel/softirq.c:646
     smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164
     kthread+0x345/0x410 kernel/kthread.c:238
     ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
    Code: 48 8b 85 e8 fe ff ff 48 8b 95 f0 fe ff ff e9 94 fb ff ff 48 89 95 f0 fe ff ff e8 81 53 6e 00 48 8b 95 f0 fe ff ff e9 62 fb ff ff <0f> 0b 48 89 cf 48 89 8d e8 fe ff ff e8 64 53 6e 00 48 8b 8d e8
    RIP: tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515 RSP: ffff8801d9b3faf8
    
    Fixes: dc841e30 ("dccp: Extend CCID packet dequeueing interface")
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
    Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
    Cc: dccp@vger.kernel.org
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    a8d7aa17
timer.c 7.28 KB