[ 130/143] ipv6: call udp_push_pending_frames when uncorking a socket with

Willy Tarreau
2014-05-12T01:42:16Z

AF_INET pending data

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

CVE-2013-4162

BugLink: http://bugs.launchpad.net/bugs/1205070

We accidentally call down to ip6_push_pending_frames when uncorking
pending AF_INET data on a ipv6 socket. This results in the following
splat (from Dave Jones):

skbuff: skb_under_panic: text:ffffffff816765f6 len:48 put:40 head:ffff88013deb6df0 data:ffff88013deb6dec tail:0x2c end:0xc0 dev:<NULL>
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:126!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in: dccp_ipv4 dccp 8021q garp bridge stp dlci mpoa snd_seq_dummy sctp fuse hidp tun bnep nfnetlink scsi_transport_iscsi rfcomm can_raw can_bcm af_802154 appletalk caif_socket can caif ipt_ULOG x25 rose af_key pppoe pppox ipx phonet irda llc2 ppp_generic slhc p8023 psnap p8022 llc crc_ccitt atm bluetooth
+netrom ax25 nfc rfkill rds af_rxrpc coretemp hwmon kvm_intel kvm crc32c_intel snd_hda_codec_realtek ghash_clmulni_intel microcode pcspkr snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep usb_debug snd_seq snd_seq_device snd_pcm e1000e snd_page_alloc snd_timer ptp snd pps_core soundcore xfs libcrc32c
CPU: 2 PID: 8095 Comm: trinity-child2 Not tainted 3.10.0-rc7+ #37
task: ffff8801f52c2520 ti: ffff8801e6430000 task.ti: ffff8801e6430000
RIP: 0010:[<ffffffff816e759c>] [<ffffffff816e759c>] skb_panic+0x63/0x65
RSP: 0018:ffff8801e6431de8 EFLAGS: 00010282
RAX: 0000000000000086 RBX: ffff8802353d3cc0 RCX: 0000000000000006
RDX: 0000000000003b90 RSI: ffff8801f52c2ca0 RDI: ffff8801f52c2520
RBP: ffff8801e6431e08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88022ea0c800
R13: ffff88022ea0cdf8 R14: ffff8802353ecb40 R15: ffffffff81cc7800
FS: 00007f5720a10740(0000) GS:ffff880244c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000005862000 CR3: 000000022843c000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
ffff88013deb6dec 000000000000002c 00000000000000c0 ffffffff81a3f6e4
ffff8801e6431e18 ffffffff8159a9aa ffff8801e6431e90 ffffffff816765f6
ffffffff810b756b 0000000700000002 ffff8801e6431e40 0000fea9292aa8c0
Call Trace:
[<ffffffff8159a9aa>] skb_push+0x3a/0x40
[<ffffffff816765f6>] ip6_push_pending_frames+0x1f6/0x4d0
[<ffffffff810b756b>] ? mark_held_locks+0xbb/0x140
[<ffffffff81694919>] udp_v6_push_pending_frames+0x2b9/0x3d0
[<ffffffff81694660>] ? udplite_getfrag+0x20/0x20
[<ffffffff8162092a>] udp_lib_setsockopt+0x1aa/0x1f0
[<ffffffff811cc5e7>] ? fget_light+0x387/0x4f0
[<ffffffff816958a4>] udpv6_setsockopt+0x34/0x40
[<ffffffff815949f4>] sock_common_setsockopt+0x14/0x20
[<ffffffff81593c31>] SyS_setsockopt+0x71/0xd0
[<ffffffff816f5d54>] tracesys+0xdd/0xe2
Code: 00 00 48 89 44 24 10 8b 87 d8 00 00 00 48 89 44 24 08 48 8b 87 e8 00 00 00 48 c7 c7 c0 04 aa 81 48 89 04 24 31 c0 e8 e1 7e ff ff <0f> 0b 55 48 89 e5 0f 0b 55 48 89 e5 0f 0b 55 48 89 e5 0f 0b 55
RIP [<ffffffff816e759c>] skb_panic+0x63/0x65
RSP <ffff8801e6431de8>

This patch adds a check if the pending data is of address family AF_INET
and directly calls udp_push_ending_frames from udp_v6_push_pending_frames
if that is the case.

This bug was found by Dave Jones with trinity.

(Also move the initialization of fl6 below the AF_INET check, even if
not strictly necessary.)

Cc: Dave Jones <davej@redhat.com>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
(back ported from commit 8822b64a0fa64a5dd1dfcf837c5b0be83f8c05d1)
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
include/net/udp.h | 1 +
net/ipv4/udp.c | 3 ++-
net/ipv6/udp.c | 7 ++++++-
3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/net/udp.h b/include/net/udp.h
index f98abd2..702bea0 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -134,6 +134,7 @@ extern void udp_err(struct sk_buff *, u32);

extern int udp_sendmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t len);
+extern int udp_push_pending_frames(struct sock *sk);
extern void udp_flush_pending_frames(struct sock *sk);

extern int udp_rcv(struct sk_buff *skb);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index dba3c01..0b2e07f 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -513,7 +513,7 @@ static void udp4_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
/*
* Push out all pending data as one UDP datagram. Socket is locked.
*/
-static int udp_push_pending_frames(struct sock *sk)
+int udp_push_pending_frames(struct sock *sk)
{
struct udp_sock *up = udp_sk(sk);
struct inet_sock *inet = inet_sk(sk);
@@ -575,6 +575,7 @@ out:
up->pending = 0;
return err;
}
+EXPORT_SYMBOL(udp_push_pending_frames);

int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t len)
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3a91859..d0367eb 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -687,11 +687,16 @@ static int udp_v6_push_pending_frames(struct sock *sk)
struct udphdr *uh;
struct udp_sock *up = udp_sk(sk);
struct inet_sock *inet = inet_sk(sk);
- struct flowi *fl = &inet->cork.fl;
+ struct flowi *fl;
int err = 0;
int is_udplite = IS_UDPLITE(sk);
__wsum csum = 0;

+ if (up->pending == AF_INET)
+ return udp_push_pending_frames(sk);
+
+ fl = &inet->cork.fl;
+
/* Grab the skbuff where UDP header space exists. */
if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
goto out;
--
1.7.12.2.21.g234cd45.dirty