From c3f24cfb3e508c70c26ee8569d537c8ca67a36c6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Nov 2016 17:14:41 -0700 Subject: dccp: do not release listeners too soon Andrey Konovalov reported following error while fuzzing with syzkaller : IPv4: Attempt to release alive inet socket ffff880068e98940 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Modules linked in: CPU: 1 PID: 3905 Comm: a.out Not tainted 4.9.0-rc3+ #333 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88006b9e0000 task.stack: ffff880068770000 RIP: 0010:[] [] selinux_socket_sock_rcv_skb+0xff/0x6a0 security/selinux/hooks.c:4639 RSP: 0018:ffff8800687771c8 EFLAGS: 00010202 RAX: ffff88006b9e0000 RBX: 1ffff1000d0eee3f RCX: 1ffff1000d1d312a RDX: 1ffff1000d1d31a6 RSI: dffffc0000000000 RDI: 0000000000000010 RBP: ffff880068777360 R08: 0000000000000000 R09: 0000000000000002 R10: dffffc0000000000 R11: 0000000000000006 R12: ffff880068e98940 R13: 0000000000000002 R14: ffff880068777338 R15: 0000000000000000 FS: 00007f00ff760700(0000) GS:ffff88006cd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020008000 CR3: 000000006a308000 CR4: 00000000000006e0 Stack: ffff8800687771e0 ffffffff812508a5 ffff8800686f3168 0000000000000007 ffff88006ac8cdfc ffff8800665ea500 0000000041b58ab3 ffffffff847b5480 ffffffff819eac60 ffff88006b9e0860 ffff88006b9e0868 ffff88006b9e07f0 Call Trace: [] security_sock_rcv_skb+0x75/0xb0 security/security.c:1317 [] sk_filter_trim_cap+0x67/0x10e0 net/core/filter.c:81 [] __sk_receive_skb+0x30/0xa00 net/core/sock.c:460 [] dccp_v4_rcv+0xdb2/0x1910 net/dccp/ipv4.c:873 [] ip_local_deliver_finish+0x332/0xad0 net/ipv4/ip_input.c:216 [< inline >] NF_HOOK_THRESH ./include/linux/netfilter.h:232 [< inline >] NF_HOOK ./include/linux/netfilter.h:255 [] ip_local_deliver+0x1c2/0x4b0 net/ipv4/ip_input.c:257 [< inline >] dst_input ./include/net/dst.h:507 [] ip_rcv_finish+0x750/0x1c40 net/ipv4/ip_input.c:396 [< inline >] NF_HOOK_THRESH ./include/linux/netfilter.h:232 [< inline >] NF_HOOK ./include/linux/netfilter.h:255 [] ip_rcv+0x96f/0x12f0 net/ipv4/ip_input.c:487 [] __netif_receive_skb_core+0x1897/0x2a50 net/core/dev.c:4213 [] __netif_receive_skb+0x2a/0x170 net/core/dev.c:4251 [] netif_receive_skb_internal+0x1b3/0x390 net/core/dev.c:4279 [] netif_receive_skb+0x48/0x250 net/core/dev.c:4303 [] tun_get_user+0xbd5/0x28a0 drivers/net/tun.c:1308 [] tun_chr_write_iter+0xda/0x190 drivers/net/tun.c:1332 [< inline >] new_sync_write fs/read_write.c:499 [] __vfs_write+0x334/0x570 fs/read_write.c:512 [] vfs_write+0x17b/0x500 fs/read_write.c:560 [< inline >] SYSC_write fs/read_write.c:607 [] SyS_write+0xd4/0x1a0 fs/read_write.c:599 [] entry_SYSCALL_64_fastpath+0x1f/0xc2 It turns out DCCP calls __sk_receive_skb(), and this broke when lookups no longer took a reference on listeners. Fix this issue by adding a @refcounted parameter to __sk_receive_skb(), so that sock_put() is used only when needed. Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood") Signed-off-by: Eric Dumazet Reported-by: Andrey Konovalov Tested-by: Andrey Konovalov Signed-off-by: David S. Miller --- net/dccp/ipv6.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/dccp/ipv6.c') diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index 3828f94b234c..09c4e19aa285 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -738,7 +738,8 @@ lookup: if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; - return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4) ? -1 : 0; + return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, + refcounted) ? -1 : 0; no_dccp_socket: if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) -- cgit v1.2.3-58-ga151 From 1aa9d1a0e7eefcc61696e147d123453fc0016005 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Nov 2016 20:30:48 -0700 Subject: ipv6: dccp: fix out of bound access in dccp_v6_err() dccp_v6_err() does not use pskb_may_pull() and might access garbage. We only need 4 bytes at the beginning of the DCCP header, like TCP, so the 8 bytes pulled in icmpv6_notify() are more than enough. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/dccp/ipv6.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'net/dccp/ipv6.c') diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index 09c4e19aa285..b2a43af967e5 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -70,7 +70,7 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, u8 type, u8 code, int offset, __be32 info) { const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data; - const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); + const struct dccp_hdr *dh; struct dccp_sock *dp; struct ipv6_pinfo *np; struct sock *sk; @@ -78,12 +78,13 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, __u64 seq; struct net *net = dev_net(skb->dev); - if (skb->len < offset + sizeof(*dh) || - skb->len < offset + __dccp_basic_hdr_len(dh)) { - __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), - ICMP6_MIB_INERRORS); - return; - } + /* Only need dccph_dport & dccph_sport which are the first + * 4 bytes in dccp header. + * Our caller (icmpv6_notify()) already pulled 8 bytes for us. + */ + BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); + BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); + dh = (struct dccp_hdr *)(skb->data + offset); sk = __inet6_lookup_established(net, &dccp_hashinfo, &hdr->daddr, dh->dccph_dport, -- cgit v1.2.3-58-ga151 From 990ff4d84408fc55942ca6644f67e361737b3d8e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 3 Nov 2016 08:59:46 -0700 Subject: ipv6: dccp: add missing bind_conflict to dccp_ipv6_mapped While fuzzing kernel with syzkaller, Andrey reported a nasty crash in inet6_bind() caused by DCCP lacking a required method. Fixes: ab1e0a13d7029 ("[SOCK] proto: Add hashinfo member to struct proto") Signed-off-by: Eric Dumazet Reported-by: Andrey Konovalov Tested-by: Andrey Konovalov Cc: Arnaldo Carvalho de Melo Acked-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/ipv6.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/dccp/ipv6.c') diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index b2a43af967e5..715e5d1dc107 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -958,6 +958,7 @@ static const struct inet_connection_sock_af_ops dccp_ipv6_mapped = { .getsockopt = ipv6_getsockopt, .addr2sockaddr = inet6_csk_addr2sockaddr, .sockaddr_len = sizeof(struct sockaddr_in6), + .bind_conflict = inet6_csk_bind_conflict, #ifdef CONFIG_COMPAT .compat_setsockopt = compat_ipv6_setsockopt, .compat_getsockopt = compat_ipv6_getsockopt, -- cgit v1.2.3-58-ga151