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Message-ID: <1397502396.4222.45.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Mon, 14 Apr 2014 12:06:36 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: nasa4836@...il.com, jchapman@...alix.com, edumazet@...gle.com,
joe@...ches.com, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [BUG] A panic caused by null pointer dereference aftering
updating to
On Mon, 2014-04-14 at 14:48 -0400, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Mon, 14 Apr 2014 11:19:26 -0700
>
> > ip_local_out() doesn't use skb->sk
>
> It does Eric.
>
Hmmm, right...
> We had just such a report with this in the backtrace, when AF_PACKET
> sends over vxlan devices.
>
> The problem is ip_mc_output().
So this means that : User socket wanted sk_mc_loop(sk), but because
vxlan changed skb->sk to internal socket, we were doing something else
anyway.
There are a lot of undocumented features here... like
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;
which socket do we want here (in ip_queue_xmit()) ?
Its interesting to see ip6_xmit() already has a 'struct sock *sk'
parameter...
This was the preliminary patch I tested :
include/net/inet6_connection_sock.h | 2 +-
include/net/inet_connection_sock.h | 2 +-
include/net/ip.h | 2 +-
net/dccp/output.c | 2 +-
net/ipv4/ip_output.c | 5 +++--
net/ipv4/tcp_output.c | 2 +-
net/ipv6/inet6_connection_sock.c | 3 +--
net/l2tp/l2tp_core.c | 4 ++--
net/l2tp/l2tp_ip.c | 2 +-
net/sctp/protocol.c | 2 +-
10 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
index f981ba7adeed..74af137304be 100644
--- a/include/net/inet6_connection_sock.h
+++ b/include/net/inet6_connection_sock.h
@@ -40,7 +40,7 @@ void inet6_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);
-int inet6_csk_xmit(struct sk_buff *skb, struct flowi *fl);
+int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu);
#endif /* _INET6_CONNECTION_SOCK_H */
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index c55aeed41ace..7a4313887568 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -36,7 +36,7 @@ struct tcp_congestion_ops;
* (i.e. things that depend on the address family)
*/
struct inet_connection_sock_af_ops {
- int (*queue_xmit)(struct sk_buff *skb, struct flowi *fl);
+ int (*queue_xmit)(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
void (*send_check)(struct sock *sk, struct sk_buff *skb);
int (*rebuild_header)(struct sock *sk);
void (*sk_rx_dst_set)(struct sock *sk, const struct sk_buff *skb);
diff --git a/include/net/ip.h b/include/net/ip.h
index 25064c28e059..77e73d293e09 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -111,7 +111,7 @@ int ip_do_nat(struct sk_buff *skb);
void ip_send_check(struct iphdr *ip);
int __ip_local_out(struct sk_buff *skb);
int ip_local_out(struct sk_buff *skb);
-int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl);
+int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
void ip_init(void);
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
int getfrag(void *from, char *to, int offset, int len,
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 8876078859da..0248e8a3460c 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -138,7 +138,7 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
- err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl);
+ err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl);
return net_xmit_eval(err);
}
return -ENOBUFS;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 1a0755fea491..7ad68b860935 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -315,9 +315,9 @@ static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
sizeof(fl4->saddr) + sizeof(fl4->daddr));
}
-int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
+/* Note: skb->sk can be different from sk, in case of tunnels */
+int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
{
- struct sock *sk = skb->sk;
struct inet_sock *inet = inet_sk(sk);
struct ip_options_rcu *inet_opt;
struct flowi4 *fl4;
@@ -389,6 +389,7 @@ packet_routed:
ip_select_ident_more(skb, &rt->dst, sk,
(skb_shinfo(skb)->gso_segs ?: 1) - 1);
+ /* TODO : should we use skb->sk here instead of sk ? */
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 699fb102e971..025e25093984 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -981,7 +981,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS,
tcp_skb_pcount(skb));
- err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl);
+ err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl);
if (likely(err <= 0))
return err;
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index c9138189415a..d4ade34ab375 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -224,9 +224,8 @@ static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
return dst;
}
-int inet6_csk_xmit(struct sk_buff *skb, struct flowi *fl_unused)
+int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused)
{
- struct sock *sk = skb->sk;
struct ipv6_pinfo *np = inet6_sk(sk);
struct flowi6 fl6;
struct dst_entry *dst;
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 47f7a5490555..a4e37d7158dc 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1131,10 +1131,10 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
skb->local_df = 1;
#if IS_ENABLED(CONFIG_IPV6)
if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
- error = inet6_csk_xmit(skb, NULL);
+ error = inet6_csk_xmit(tunnel->sock, skb, NULL);
else
#endif
- error = ip_queue_xmit(skb, fl);
+ error = ip_queue_xmit(tunnel->sock, skb, fl);
/* Update stats */
if (error >= 0) {
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 0b44d855269c..3397fe6897c0 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -487,7 +487,7 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
xmit:
/* Queue the packet to IP for output */
- rc = ip_queue_xmit(skb, &inet->cork.fl);
+ rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
rcu_read_unlock();
error:
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 4e1d0fcb028e..c09757fbf803 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -957,7 +957,7 @@ static inline int sctp_v4_xmit(struct sk_buff *skb,
SCTP_INC_STATS(sock_net(&inet->sk), SCTP_MIB_OUTSCTPPACKS);
- return ip_queue_xmit(skb, &transport->fl);
+ return ip_queue_xmit(&inet->sk, skb, &transport->fl);
}
static struct sctp_af sctp_af_inet;
--
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