3.2.46-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <eduma...@google.com>
[ Upstream commit f77d602124d865c38705df7fa25c03de9c284ad2 ]
We have seen multiple NULL dereferences in __inet6_lookup_established()
After analysis, I found that inet6_sk() could be NULL while the
check for sk_family == AF_INET6 was true.
Bug was added in linux-2.6.29 when RCU lookups were introduced in UDP
and TCP stacks.
Once an IPv6 socket, using SLAB_DESTROY_BY_RCU is inserted in a hash
table, we no longer can clear pinet6 field.
This patch extends logic used in commit fcbdf09d9652c891
("net: fix nulls list corruptions in sk_prot_alloc")
TCP/UDP/UDPLite IPv6 protocols provide their own .clear_sk() method
to make sure we do not clear pinet6 field.
At socket clone phase, we do not really care, as cloning the parent (non
NULL) pinet6 is not adding a fatal race.
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
include/net/sock.h | 12 ++++++++++++
net/core/sock.c | 12 ------------
net/ipv6/tcp_ipv6.c | 12 ++++++++++++
net/ipv6/udp.c | 13 ++++++++++++-
net/ipv6/udp_impl.h | 2 ++
net/ipv6/udplite.c | 2 +-
6 files changed, 39 insertions(+), 14 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index ddf523c..e6454b6 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -734,6 +734,18 @@ struct inet_hashinfo;
struct raw_hashinfo;
struct module;
+/*
+ * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
+ * un-modified. Special care is taken when initializing object to zero.
+ */
+static inline void sk_prot_clear_nulls(struct sock *sk, int size)
+{
+ if (offsetof(struct sock, sk_node.next) != 0)
+ memset(sk, 0, offsetof(struct sock, sk_node.next));
+ memset(&sk->sk_node.pprev, 0,
+ size - offsetof(struct sock, sk_node.pprev));
+}
+
/* Networking protocol blocks we attach to sockets.
* socket layer -> transport layer interface
* transport -> network interface is defined by struct inet_proto
diff --git a/net/core/sock.c b/net/core/sock.c
index 2c73adf..8a2c2dd 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1021,18 +1021,6 @@ static void sock_copy(struct sock *nsk, const struct
sock *osk)
#endif
}
-/*
- * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
- * un-modified. Special care is taken when initializing object to zero.
- */
-static inline void sk_prot_clear_nulls(struct sock *sk, int size)
-{
- if (offsetof(struct sock, sk_node.next) != 0)
- memset(sk, 0, offsetof(struct sock, sk_node.next));
- memset(&sk->sk_node.pprev, 0,
- size - offsetof(struct sock, sk_node.pprev));
-}
-
void sk_prot_clear_portaddr_nulls(struct sock *sk, int size)
{
unsigned long nulls1, nulls2;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index db10805..c69358c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2196,6 +2196,17 @@ void tcp6_proc_exit(struct net *net)
}
#endif
+static void tcp_v6_clear_sk(struct sock *sk, int size)
+{
+ struct inet_sock *inet = inet_sk(sk);
+
+ /* we do not want to clear pinet6 field, because of RCU lookups */
+ sk_prot_clear_nulls(sk, offsetof(struct inet_sock, pinet6));
+
+ size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
+ memset(&inet->pinet6 + 1, 0, size);
+}
+
struct proto tcpv6_prot = {
.name = "TCPv6",
.owner = THIS_MODULE,
@@ -2235,6 +2246,7 @@ struct proto tcpv6_prot = {
.compat_setsockopt = compat_tcp_setsockopt,
.compat_getsockopt = compat_tcp_getsockopt,
#endif
+ .clear_sk = tcp_v6_clear_sk,
};
static const struct inet6_protocol tcpv6_protocol = {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8c25419..20f0812 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1453,6 +1453,17 @@ void udp6_proc_exit(struct net *net) {
}
#endif /* CONFIG_PROC_FS */
+void udp_v6_clear_sk(struct sock *sk, int size)
+{
+ struct inet_sock *inet = inet_sk(sk);
+
+ /* we do not want to clear pinet6 field, because of RCU lookups */
+ sk_prot_clear_portaddr_nulls(sk, offsetof(struct inet_sock, pinet6));
+
+ size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
+ memset(&inet->pinet6 + 1, 0, size);
+}
+
/* ------------------------------------------------------------------------ */
struct proto udpv6_prot = {
@@ -1483,7 +1494,7 @@ struct proto udpv6_prot = {
.compat_setsockopt = compat_udpv6_setsockopt,
.compat_getsockopt = compat_udpv6_getsockopt,
#endif
- .clear_sk = sk_prot_clear_portaddr_nulls,
+ .clear_sk = udp_v6_clear_sk,
};
static struct inet_protosw udpv6_protosw = {
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
index d757104..4691ed5 100644
--- a/net/ipv6/udp_impl.h
+++ b/net/ipv6/udp_impl.h
@@ -31,6 +31,8 @@ extern int udpv6_recvmsg(struct kiocb *iocb, struct sock
*sk,
extern int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb);
extern void udpv6_destroy_sock(struct sock *sk);
+extern void udp_v6_clear_sk(struct sock *sk, int size);
+
#ifdef CONFIG_PROC_FS
extern int udp6_seq_show(struct seq_file *seq, void *v);
#endif
diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 1d08e21..dfcc4be 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -56,7 +56,7 @@ struct proto udplitev6_prot = {
.compat_setsockopt = compat_udpv6_setsockopt,
.compat_getsockopt = compat_udpv6_getsockopt,
#endif
- .clear_sk = sk_prot_clear_portaddr_nulls,
+ .clear_sk = udp_v6_clear_sk,
};
static struct inet_protosw udplite6_protosw = {
--
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