Oops on transmit HTTP request to backend server

[krizhanovsky]

Not always reproducable.

    [tempesta]   parser: Req_Hdr(16:0): c=0xd(.), r=-2
    [tempesta]   parser: Req_HdrDone(77:0): c=0xa(.), r=-2
    [tempesta]   request parsed: len=280 parsed=280 res=0
    [sync_socket]   ss_send:93 is_queue_empty=0 tcp_send_head(sk)=ffff88003d5358c0 sk->sk_state=1
    BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
    IP: [<ffffffff82401cfa>] tcp_ack+0x506/0xb94
    PGD 3cd41067 PUD 3d17c067 PMD 0 
    Oops: 0002 [#1] SMP 
    Modules linked in: tempesta_fw(O) tempesta_db(O) sync_socket(O) i2c_piix4 floppy
    CPU: 1 PID: 11 Comm: ksoftirqd/1 Tainted: G           O 3.10.10+ #7
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
    task: ffff88003dcd6300 ti: ffff88003dcd8000 task.ti: ffff88003dcd8000
    RIP: 0010:[<ffffffff82401cfa>]  [<ffffffff82401cfa>] tcp_ack+0x506/0xb94
    RSP: 0018:ffff88003dcd99e8  EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000204 RCX: ffff88003d5358c0
    RDX: 0000000000000000 RSI: 0000000000000200 RDI: 00000000e889a0a2
    RBP: ffff88003dcd9aa8 R08: 0000000024e92d00 R09: 0000000000000001
    R10: 0000000000000001 R11: 000000000000ea9f R12: 000000003c6113bc
    R13: 0000000000000001 R14: 0000000000000000 R15: ffff880037b66080
    FS:  0000000000000000(0000) GS:ffff88003fd00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    CR2: 0000000000000008 CR3: 000000003d129000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Stack:
     ffff88003dcd9a68 ffffffff82405559 0000000000000020 0000000000000000
     ffff880037b66188 0000000000000000 0000000000000000 0000000100000000
     0000000100000000 0000000000000000 000000000000817c 0000000000000001
    Call Trace:
     [<ffffffff82405559>] ? tcp_transmit_skb+0x6a7/0x70c
     [<ffffffff82407606>] ? tcp_send_ack+0xdb/0xe0
     [<ffffffff82402c73>] tcp_rcv_established+0x602/0x6ed
     [<ffffffff824092f9>] tcp_v4_do_rcv+0xb9/0x2e0
     [<ffffffff821e2c78>] ? security_sock_rcv_skb+0x11/0x13
     [<ffffffff823cae16>] ? sk_filter+0x31/0xa1
     [<ffffffff8240ba85>] tcp_v4_rcv+0x394/0x6f0

[krizhanovsky]

Fixed in 502b948