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Message-ID: <20160512232203.12606.41050.stgit@localhost.localdomain>
Date: Thu, 12 May 2016 16:23:44 -0700
From: Alexander Duyck <aduyck@...antis.com>
To: netdev@...r.kernel.org, davem@...emloft.net,
alexander.duyck@...il.com
Cc: tgraf@...g.ch, tom@...bertland.com, jbenc@...hat.com,
eric.dumazet@...il.com
Subject: [net-next PATCH v3] udp: Resolve NULL pointer dereference over
flow-based vxlan device
While testing an OpenStack configuration using VXLANs I saw the following
call trace:
RIP: 0010:[<ffffffff815fad49>] udp4_lib_lookup_skb+0x49/0x80
RSP: 0018:ffff88103867bc50 EFLAGS: 00010286
RAX: ffff88103269bf00 RBX: ffff88103269bf00 RCX: 00000000ffffffff
RDX: 0000000000004300 RSI: 0000000000000000 RDI: ffff880f2932e780
RBP: ffff88103867bc60 R08: 0000000000000000 R09: 000000009001a8c0
R10: 0000000000004400 R11: ffffffff81333a58 R12: ffff880f2932e794
R13: 0000000000000014 R14: 0000000000000014 R15: ffffe8efbfd89ca0
FS: 0000000000000000(0000) GS:ffff88103fd80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000488 CR3: 0000000001c06000 CR4: 00000000001426e0
Stack:
ffffffff81576515 ffffffff815733c0 ffff88103867bc98 ffffffff815fcc17
ffff88103269bf00 ffffe8efbfd89ca0 0000000000000014 0000000000000080
ffffe8efbfd89ca0 ffff88103867bcc8 ffffffff815fcf8b ffff880f2932e794
Call Trace:
[<ffffffff81576515>] ? skb_checksum+0x35/0x50
[<ffffffff815733c0>] ? skb_push+0x40/0x40
[<ffffffff815fcc17>] udp_gro_receive+0x57/0x130
[<ffffffff815fcf8b>] udp4_gro_receive+0x10b/0x2c0
[<ffffffff81605863>] inet_gro_receive+0x1d3/0x270
[<ffffffff81589e59>] dev_gro_receive+0x269/0x3b0
[<ffffffff8158a1b8>] napi_gro_receive+0x38/0x120
[<ffffffffa0871297>] gro_cell_poll+0x57/0x80 [vxlan]
[<ffffffff815899d0>] net_rx_action+0x160/0x380
[<ffffffff816965c7>] __do_softirq+0xd7/0x2c5
[<ffffffff8107d969>] run_ksoftirqd+0x29/0x50
[<ffffffff8109a50f>] smpboot_thread_fn+0x10f/0x160
[<ffffffff8109a400>] ? sort_range+0x30/0x30
[<ffffffff81096da8>] kthread+0xd8/0xf0
[<ffffffff81693c82>] ret_from_fork+0x22/0x40
[<ffffffff81096cd0>] ? kthread_park+0x60/0x60
The following trace is seen when receiving a DHCP request over a flow-based
VXLAN tunnel. I believe this is caused by the metadata dst having a NULL
dev value and as a result dev_net(dev) is causing a NULL pointer dereference.
To resolve this I am replacing the check for skb_dst(skb)->dev with just
skb->dev. This makes sense as the callers of this function are usually in
the receive path and as such skb->dev should always be populated. In
addition other functions in the area where these are called are already
using dev_net(skb->dev) to determine the namespace the UDP packet belongs
in.
Fixes: 63058308cd55 ("udp: Add udp6_lib_lookup_skb and udp4_lib_lookup_skb")
Signed-off-by: Alexander Duyck <aduyck@...antis.com>
---
v2: Replaced skb_dst(skb)->dev == NULL test with skb_valid_dst(skb).
Added update for IPv6 as well since issue would affect both.
v3: Dropped use of skb_dst(skb) entirely and instead just used skb->dev.
net/ipv4/udp.c | 10 ++--------
net/ipv6/udp.c | 8 +++-----
2 files changed, 5 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f67f52ba4809..2e3ebfe5549e 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -604,7 +604,7 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
{
const struct iphdr *iph = ip_hdr(skb);
- return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport,
+ return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
iph->daddr, dport, inet_iif(skb),
udptable, skb);
}
@@ -612,13 +612,7 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
__be16 sport, __be16 dport)
{
- const struct iphdr *iph = ip_hdr(skb);
- const struct net_device *dev =
- skb_dst(skb) ? skb_dst(skb)->dev : skb->dev;
-
- return __udp4_lib_lookup(dev_net(dev), iph->saddr, sport,
- iph->daddr, dport, inet_iif(skb),
- &udp_table, skb);
+ return __udp4_lib_lookup_skb(skb, sport, dport, &udp_table);
}
EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index aca06094110f..2ba6a77a8815 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -315,13 +315,13 @@ static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
__be16 sport, __be16 dport,
struct udp_table *udptable)
{
- struct sock *sk;
const struct ipv6hdr *iph = ipv6_hdr(skb);
+ struct sock *sk;
sk = skb_steal_sock(skb);
if (unlikely(sk))
return sk;
- return __udp6_lib_lookup(dev_net(skb_dst(skb)->dev), &iph->saddr, sport,
+ return __udp6_lib_lookup(dev_net(skb->dev), &iph->saddr, sport,
&iph->daddr, dport, inet6_iif(skb),
udptable, skb);
}
@@ -330,10 +330,8 @@ struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
__be16 sport, __be16 dport)
{
const struct ipv6hdr *iph = ipv6_hdr(skb);
- const struct net_device *dev =
- skb_dst(skb) ? skb_dst(skb)->dev : skb->dev;
- return __udp6_lib_lookup(dev_net(dev), &iph->saddr, sport,
+ return __udp6_lib_lookup(dev_net(skb->dev), &iph->saddr, sport,
&iph->daddr, dport, inet6_iif(skb),
&udp_table, skb);
}
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