From 6edafaaf6f5e70ef1e620ff01bd6bacebe1e0718 Mon Sep 17 00:00:00 2001 From: Gui Jianfeng Date: Wed, 6 Aug 2008 23:50:04 -0700 Subject: [PATCH] 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 --- include/net/request_sock.h | 2 +- net/dccp/dccp.h | 3 ++- net/dccp/minisocks.c | 3 ++- net/ipv4/tcp_ipv4.c | 4 ++-- net/ipv4/tcp_minisocks.c | 2 +- net/ipv6/tcp_ipv6.c | 8 +++++--- 6 files changed, 13 insertions(+), 9 deletions(-) diff --git a/include/net/request_sock.h b/include/net/request_sock.h index 8d6e991..cac811e 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -33,7 +33,7 @@ struct request_sock_ops { struct kmem_cache *slab; int (*rtx_syn_ack)(struct sock *sk, struct request_sock *req); - void (*send_ack)(struct sk_buff *skb, + void (*send_ack)(struct sock *sk, struct sk_buff *skb, struct request_sock *req); void (*send_reset)(struct sock *sk, struct sk_buff *skb); diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 1c2e3ec..b4bc6e0 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -229,7 +229,8 @@ extern void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb); extern int dccp_retransmit_skb(struct sock *sk); extern void dccp_send_ack(struct sock *sk); -extern void dccp_reqsk_send_ack(struct sk_buff *sk, struct request_sock *rsk); +extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, + struct request_sock *rsk); extern void dccp_send_sync(struct sock *sk, const u64 seq, const enum dccp_pkt_type pkt_type); diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c index 66dca5b..b2804e2d 100644 --- a/net/dccp/minisocks.c +++ b/net/dccp/minisocks.c @@ -296,7 +296,8 @@ int dccp_child_process(struct sock *parent, struct sock *child, EXPORT_SYMBOL_GPL(dccp_child_process); -void dccp_reqsk_send_ack(struct sk_buff *skb, struct request_sock *rsk) +void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, + struct request_sock *rsk) { DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 91a8cfd..44c1e93 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -687,14 +687,14 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) inet_twsk_put(tw); } -static void tcp_v4_reqsk_send_ack(struct sk_buff *skb, +static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, struct request_sock *req) { tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, req->ts_recent, 0, - tcp_v4_md5_do_lookup(skb->sk, ip_hdr(skb)->daddr)); + tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr)); } /* diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 204c421..6d286f5 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; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 78185a4..5b90b36 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -69,7 +69,8 @@ #include static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb); -static void tcp_v6_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req); +static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, + struct request_sock *req); static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb); @@ -1138,10 +1139,11 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb) inet_twsk_put(tw); } -static void tcp_v6_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req) +static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, + struct request_sock *req) { tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, req->ts_recent, - tcp_v6_md5_do_lookup(skb->sk, &ipv6_hdr(skb)->daddr)); + tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr)); } -- 2.7.4