From 6edafaaf6f5e70ef1e620ff01bd6bacebe1e0718 Mon Sep 17 00:00:00 2001 From: Gui Jianfeng Date: Wed, 6 Aug 2008 23:50:04 -0700 Subject: 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: [] 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:[] 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] [] tcp_v4_reqsk_send_ack+0x17/0x35 [ 302.907060] [] tcp_check_req+0x156/0x372 [ 302.910082] [] printk+0x14/0x18 [ 302.912868] [] tcp_v4_do_rcv+0x1d3/0x2bf [ 302.917423] [] tcp_v4_rcv+0x563/0x5b9 [ 302.920453] [] ip_local_deliver_finish+0xe8/0x183 [ 302.923865] [] ip_rcv_finish+0x286/0x2a3 [ 302.928569] [] dev_alloc_skb+0x11/0x25 [ 302.931563] [] netif_receive_skb+0x2d6/0x33a [ 302.934914] [] pcnet32_poll+0x333/0x680 [pcnet32] [ 302.938735] [] net_rx_action+0x5c/0xfe [ 302.941792] [] __do_softirq+0x5d/0xc1 [ 302.944788] [] __do_softirq+0x0/0xc1 [ 302.948999] [] do_softirq+0x55/0x88 [ 302.951870] [] handle_fasteoi_irq+0x0/0xa4 [ 302.954986] [] irq_exit+0x35/0x69 [ 302.959081] [] do_IRQ+0x99/0xae [ 302.961896] [] common_interrupt+0x23/0x28 [ 302.966279] [] default_idle+0x2a/0x3d [ 302.969212] [] 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: [] 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 Signed-off-by: David S. Miller --- net/ipv4/tcp_minisocks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_minisocks.c') diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 204c42162660..6d286f58c00d 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -609,7 +609,7 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb, tcp_rsk(req)->rcv_isn + 1, tcp_rsk(req)->rcv_isn + 1 + req->rcv_wnd)) { /* Out of window: send ACK and drop. */ if (!(flg & TCP_FLAG_RST)) - req->rsk_ops->send_ack(skb, req); + req->rsk_ops->send_ack(sk, skb, req); if (paws_reject) NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED); return NULL; -- cgit v1.2.3 From 2aaab9a0ccfd2ccf1c957cc2120da8d5593955c5 Mon Sep 17 00:00:00 2001 From: Adam Langley Date: Thu, 7 Aug 2008 20:27:45 -0700 Subject: tcp: (whitespace only) fix confusing indentation The indentation in part of tcp_minisocks makes it look like one of the if statements is much more important than it actually is. Signed-off-by: Adam Langley Signed-off-by: David S. Miller --- net/ipv4/tcp_minisocks.c | 138 +++++++++++++++++++++++------------------------ 1 file changed, 68 insertions(+), 70 deletions(-) (limited to 'net/ipv4/tcp_minisocks.c') diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 6d286f58c00d..f976fc57892c 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -618,89 +618,87 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb, /* In sequence, PAWS is OK. */ if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_isn + 1)) - req->ts_recent = tmp_opt.rcv_tsval; + req->ts_recent = tmp_opt.rcv_tsval; - if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { - /* Truncate SYN, it is out of window starting - at tcp_rsk(req)->rcv_isn + 1. */ - flg &= ~TCP_FLAG_SYN; - } + if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { + /* Truncate SYN, it is out of window starting + at tcp_rsk(req)->rcv_isn + 1. */ + flg &= ~TCP_FLAG_SYN; + } - /* RFC793: "second check the RST bit" and - * "fourth, check the SYN bit" - */ - if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) { - TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS); - goto embryonic_reset; - } + /* RFC793: "second check the RST bit" and + * "fourth, check the SYN bit" + */ + if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) { + TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS); + goto embryonic_reset; + } - /* ACK sequence verified above, just make sure ACK is - * set. If ACK not set, just silently drop the packet. - */ - if (!(flg & TCP_FLAG_ACK)) - return NULL; - - /* If TCP_DEFER_ACCEPT is set, drop bare ACK. */ - if (inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && - TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { - inet_rsk(req)->acked = 1; - return NULL; - } + /* ACK sequence verified above, just make sure ACK is + * set. If ACK not set, just silently drop the packet. + */ + if (!(flg & TCP_FLAG_ACK)) + return NULL; - /* OK, ACK is valid, create big socket and - * feed this segment to it. It will repeat all - * the tests. THIS SEGMENT MUST MOVE SOCKET TO - * ESTABLISHED STATE. If it will be dropped after - * socket is created, wait for troubles. - */ - child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, - req, NULL); - if (child == NULL) - goto listen_overflow; + /* If TCP_DEFER_ACCEPT is set, drop bare ACK. */ + if (inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && + TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { + inet_rsk(req)->acked = 1; + return NULL; + } + + /* OK, ACK is valid, create big socket and + * feed this segment to it. It will repeat all + * the tests. THIS SEGMENT MUST MOVE SOCKET TO + * ESTABLISHED STATE. If it will be dropped after + * socket is created, wait for troubles. + */ + child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); + if (child == NULL) + goto listen_overflow; #ifdef CONFIG_TCP_MD5SIG - else { - /* Copy over the MD5 key from the original socket */ - struct tcp_md5sig_key *key; - struct tcp_sock *tp = tcp_sk(sk); - key = tp->af_specific->md5_lookup(sk, child); - if (key != NULL) { - /* - * We're using one, so create a matching key on the - * newsk structure. If we fail to get memory then we - * end up not copying the key across. Shucks. - */ - char *newkey = kmemdup(key->key, key->keylen, - GFP_ATOMIC); - if (newkey) { - if (!tcp_alloc_md5sig_pool()) - BUG(); - tp->af_specific->md5_add(child, child, - newkey, - key->keylen); - } + else { + /* Copy over the MD5 key from the original socket */ + struct tcp_md5sig_key *key; + struct tcp_sock *tp = tcp_sk(sk); + key = tp->af_specific->md5_lookup(sk, child); + if (key != NULL) { + /* + * We're using one, so create a matching key on the + * newsk structure. If we fail to get memory then we + * end up not copying the key across. Shucks. + */ + char *newkey = kmemdup(key->key, key->keylen, + GFP_ATOMIC); + if (newkey) { + if (!tcp_alloc_md5sig_pool()) + BUG(); + tp->af_specific->md5_add(child, child, newkey, + key->keylen); } } + } #endif - inet_csk_reqsk_queue_unlink(sk, req, prev); - inet_csk_reqsk_queue_removed(sk, req); + inet_csk_reqsk_queue_unlink(sk, req, prev); + inet_csk_reqsk_queue_removed(sk, req); - inet_csk_reqsk_queue_add(sk, req, child); - return child; + inet_csk_reqsk_queue_add(sk, req, child); + return child; - listen_overflow: - if (!sysctl_tcp_abort_on_overflow) { - inet_rsk(req)->acked = 1; - return NULL; - } +listen_overflow: + if (!sysctl_tcp_abort_on_overflow) { + inet_rsk(req)->acked = 1; + return NULL; + } - embryonic_reset: - NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS); - if (!(flg & TCP_FLAG_RST)) - req->rsk_ops->send_reset(sk, skb); +embryonic_reset: + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS); + if (!(flg & TCP_FLAG_RST)) + req->rsk_ops->send_reset(sk, skb); - inet_csk_reqsk_queue_drop(sk, req, prev); - return NULL; + inet_csk_reqsk_queue_drop(sk, req, prev); + return NULL; } /* -- cgit v1.2.3