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![Gui Jianfeng](/assets/img/avatar_default.png)
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>
248 lines
6.4 KiB
C
248 lines
6.4 KiB
C
/*
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* NET Generic infrastructure for Network protocols.
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*
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* Definitions for request_sock
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*
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* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* From code originally in include/net/tcp.h
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _REQUEST_SOCK_H
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#define _REQUEST_SOCK_H
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/bug.h>
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#include <net/sock.h>
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struct request_sock;
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struct sk_buff;
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struct dst_entry;
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struct proto;
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struct request_sock_ops {
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int family;
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int obj_size;
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struct kmem_cache *slab;
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int (*rtx_syn_ack)(struct sock *sk,
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struct request_sock *req);
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void (*send_ack)(struct sock *sk, struct sk_buff *skb,
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struct request_sock *req);
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void (*send_reset)(struct sock *sk,
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struct sk_buff *skb);
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void (*destructor)(struct request_sock *req);
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};
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/* struct request_sock - mini sock to represent a connection request
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*/
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struct request_sock {
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struct request_sock *dl_next; /* Must be first member! */
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u16 mss;
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u8 retrans;
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u8 cookie_ts; /* syncookie: encode tcpopts in timestamp */
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/* The following two fields can be easily recomputed I think -AK */
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u32 window_clamp; /* window clamp at creation time */
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u32 rcv_wnd; /* rcv_wnd offered first time */
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u32 ts_recent;
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unsigned long expires;
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const struct request_sock_ops *rsk_ops;
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struct sock *sk;
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u32 secid;
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u32 peer_secid;
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};
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static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
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{
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struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
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if (req != NULL)
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req->rsk_ops = ops;
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return req;
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}
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static inline void __reqsk_free(struct request_sock *req)
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{
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kmem_cache_free(req->rsk_ops->slab, req);
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}
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static inline void reqsk_free(struct request_sock *req)
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{
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req->rsk_ops->destructor(req);
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__reqsk_free(req);
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}
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extern int sysctl_max_syn_backlog;
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/** struct listen_sock - listen state
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*
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* @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
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*/
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struct listen_sock {
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u8 max_qlen_log;
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/* 3 bytes hole, try to use */
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int qlen;
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int qlen_young;
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int clock_hand;
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u32 hash_rnd;
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u32 nr_table_entries;
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struct request_sock *syn_table[0];
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};
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/** struct request_sock_queue - queue of request_socks
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*
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* @rskq_accept_head - FIFO head of established children
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* @rskq_accept_tail - FIFO tail of established children
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* @rskq_defer_accept - User waits for some data after accept()
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* @syn_wait_lock - serializer
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*
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* %syn_wait_lock is necessary only to avoid proc interface having to grab the main
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* lock sock while browsing the listening hash (otherwise it's deadlock prone).
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*
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* This lock is acquired in read mode only from listening_get_next() seq_file
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* op and it's acquired in write mode _only_ from code that is actively
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* changing rskq_accept_head. All readers that are holding the master sock lock
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* don't need to grab this lock in read mode too as rskq_accept_head. writes
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* are always protected from the main sock lock.
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*/
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struct request_sock_queue {
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struct request_sock *rskq_accept_head;
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struct request_sock *rskq_accept_tail;
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rwlock_t syn_wait_lock;
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u8 rskq_defer_accept;
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/* 3 bytes hole, try to pack */
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struct listen_sock *listen_opt;
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};
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extern int reqsk_queue_alloc(struct request_sock_queue *queue,
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unsigned int nr_table_entries);
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extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
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extern void reqsk_queue_destroy(struct request_sock_queue *queue);
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static inline struct request_sock *
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reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
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{
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struct request_sock *req = queue->rskq_accept_head;
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queue->rskq_accept_head = NULL;
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return req;
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}
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static inline int reqsk_queue_empty(struct request_sock_queue *queue)
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{
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return queue->rskq_accept_head == NULL;
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}
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static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
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struct request_sock *req,
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struct request_sock **prev_req)
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{
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write_lock(&queue->syn_wait_lock);
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*prev_req = req->dl_next;
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write_unlock(&queue->syn_wait_lock);
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}
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static inline void reqsk_queue_add(struct request_sock_queue *queue,
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struct request_sock *req,
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struct sock *parent,
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struct sock *child)
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{
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req->sk = child;
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sk_acceptq_added(parent);
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if (queue->rskq_accept_head == NULL)
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queue->rskq_accept_head = req;
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else
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queue->rskq_accept_tail->dl_next = req;
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queue->rskq_accept_tail = req;
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req->dl_next = NULL;
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}
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static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
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{
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struct request_sock *req = queue->rskq_accept_head;
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WARN_ON(req == NULL);
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queue->rskq_accept_head = req->dl_next;
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if (queue->rskq_accept_head == NULL)
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queue->rskq_accept_tail = NULL;
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return req;
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}
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static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
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struct sock *parent)
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{
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struct request_sock *req = reqsk_queue_remove(queue);
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struct sock *child = req->sk;
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WARN_ON(child == NULL);
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sk_acceptq_removed(parent);
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__reqsk_free(req);
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return child;
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}
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static inline int reqsk_queue_removed(struct request_sock_queue *queue,
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struct request_sock *req)
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{
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struct listen_sock *lopt = queue->listen_opt;
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if (req->retrans == 0)
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--lopt->qlen_young;
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return --lopt->qlen;
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}
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static inline int reqsk_queue_added(struct request_sock_queue *queue)
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{
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struct listen_sock *lopt = queue->listen_opt;
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const int prev_qlen = lopt->qlen;
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lopt->qlen_young++;
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lopt->qlen++;
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return prev_qlen;
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}
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static inline int reqsk_queue_len(const struct request_sock_queue *queue)
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{
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return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
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}
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static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
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{
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return queue->listen_opt->qlen_young;
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}
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static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
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{
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return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
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}
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static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
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u32 hash, struct request_sock *req,
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unsigned long timeout)
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{
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struct listen_sock *lopt = queue->listen_opt;
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req->expires = jiffies + timeout;
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req->retrans = 0;
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req->sk = NULL;
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req->dl_next = lopt->syn_table[hash];
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write_lock(&queue->syn_wait_lock);
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lopt->syn_table[hash] = req;
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write_unlock(&queue->syn_wait_lock);
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}
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#endif /* _REQUEST_SOCK_H */
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