tcp: Fix kernel panic when calling tcp_v(4/6)_md5_do_lookup
If the following packet flow happen, kernel will panic.
MathineA MathineB
SYN
---------------------->
SYN+ACK
<----------------------
ACK(bad seq)
---------------------->
When a bad seq ACK is received, tcp_v4_md5_do_lookup(skb->sk, ip_hdr(skb)->daddr))
is finally called by tcp_v4_reqsk_send_ack(), but the first parameter(skb->sk) is
NULL at that moment, so kernel panic happens.
This patch fixes this bug.
OOPS output is as following:
[ 302.812793] IP: [<c05cfaa6>] tcp_v4_md5_do_lookup+0x12/0x42
[ 302.817075] Oops: 0000 [#1] SMP
[ 302.819815] Modules linked in: ipv6 loop dm_multipath rtc_cmos rtc_core rtc_lib pcspkr pcnet32 mii i2c_piix4 parport_pc i2c_core parport ac button ata_piix libata dm_mod mptspi mptscsih mptbase scsi_transport_spi sd_mod scsi_mod crc_t10dif ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: scsi_wait_scan]
[ 302.849946]
[ 302.851198] Pid: 0, comm: swapper Not tainted (2.6.27-rc1-guijf #5)
[ 302.855184] EIP: 0060:[<c05cfaa6>] EFLAGS: 00010296 CPU: 0
[ 302.858296] EIP is at tcp_v4_md5_do_lookup+0x12/0x42
[ 302.861027] EAX: 0000001e EBX: 00000000 ECX: 00000046 EDX: 00000046
[ 302.864867] ESI: ceb69e00 EDI: 1467a8c0 EBP: cf75f180 ESP: c0792e54
[ 302.868333] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
[ 302.871287] Process swapper (pid: 0, ti=c0792000 task=c0712340 task.ti=c0746000)
[ 302.875592] Stack: c06f413a 00000000 cf75f180 ceb69e00 00000000 c05d0d86 000016d0 ceac5400
[ 302.883275] c05d28f8 000016d0 ceb69e00 ceb69e20 681bf6e3 00001000 00000000 0a67a8c0
[ 302.890971] ceac5400 c04250a3 c06f413a c0792eb0 c0792edc cf59a620 cf59a620 cf59a634
[ 302.900140] Call Trace:
[ 302.902392] [<c05d0d86>] tcp_v4_reqsk_send_ack+0x17/0x35
[ 302.907060] [<c05d28f8>] tcp_check_req+0x156/0x372
[ 302.910082] [<c04250a3>] printk+0x14/0x18
[ 302.912868] [<c05d0aa1>] tcp_v4_do_rcv+0x1d3/0x2bf
[ 302.917423] [<c05d26be>] tcp_v4_rcv+0x563/0x5b9
[ 302.920453] [<c05bb20f>] ip_local_deliver_finish+0xe8/0x183
[ 302.923865] [<c05bb10a>] ip_rcv_finish+0x286/0x2a3
[ 302.928569] [<c059e438>] dev_alloc_skb+0x11/0x25
[ 302.931563] [<c05a211f>] netif_receive_skb+0x2d6/0x33a
[ 302.934914] [<d0917941>] pcnet32_poll+0x333/0x680 [pcnet32]
[ 302.938735] [<c05a3b48>] net_rx_action+0x5c/0xfe
[ 302.941792] [<c042856b>] __do_softirq+0x5d/0xc1
[ 302.944788] [<c042850e>] __do_softirq+0x0/0xc1
[ 302.948999] [<c040564b>] do_softirq+0x55/0x88
[ 302.951870] [<c04501b1>] handle_fasteoi_irq+0x0/0xa4
[ 302.954986] [<c04284da>] irq_exit+0x35/0x69
[ 302.959081] [<c0405717>] do_IRQ+0x99/0xae
[ 302.961896] [<c040422b>] common_interrupt+0x23/0x28
[ 302.966279] [<c040819d>] default_idle+0x2a/0x3d
[ 302.969212] [<c0402552>] cpu_idle+0xb2/0xd2
[ 302.972169] =======================
[ 302.974274] Code: fc ff 84 d2 0f 84 df fd ff ff e9 34 fe ff ff 83 c4 0c 5b 5e 5f 5d c3 90 90 57 89 d7 56 53 89 c3 50 68 3a 41 6f c0 e8 e9 55 e5 ff <8b> 93 9c 04 00 00 58 85 d2 59 74 1e 8b 72 10 31 db 31 c9 85 f6
[ 303.011610] EIP: [<c05cfaa6>] tcp_v4_md5_do_lookup+0x12/0x42 SS:ESP 0068:c0792e54
[ 303.018360] Kernel panic - not syncing: Fatal exception in interrupt
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
6 files changed