First bug was added in commit ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv") : Tom missed that ipv4 udp messages could be received on AF_INET6 socket. ip_cmsg_recv(msg, skb) should have been replaced by ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr));

Then commit e6afc8ace6dd ("udp: remove headers from UDP packets before queueing") forgot to adjust the offsets now UDP headers are pulled before skb are put in receive queue.

Fixes ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv")

Fixes e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")

Signed-off-by Eric Dumazet <[email protected]>

Cc Sam Kumar <[email protected]>

Cc Willem de Bruijn <[email protected]>

Tested-by Willem de Bruijn <[email protected]>

Signed-off-by David S. Miller <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 include/net/ip.h       |    4 ++--
 net/ipv4/ip_sockglue.c |   11 ++++++-----
 net/ipv4/udp.c         |    2 +-
 net/ipv6/udp.c         |    3 ++-
 4 files changed, 11 insertions(+), 9 deletions(-)

include/net/ip.h +2 -2

@@ -549,7 +549,7 @@ int ip_options_rcv_srr(struct sk_buff *s
  */
 
 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
-void ip_cmsg_recv_offset(struct msghdr *msg, struct sk_buff *skb, int offset);
+void ip_cmsg_recv_offset(struct msghdr *msg, struct sk_buff *skb, int tlen, int offset);
 int ip_cmsg_send(struct sock *sk, struct msghdr *msg,
 		 struct ipcm_cookie *ipc, bool allow_ipv6);
 int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,

@@ -571,7 +571,7 @@ void ip_local_error(struct sock *sk, int
 
 static inline void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
 {
-	ip_cmsg_recv_offset(msg, skb, 0);
+	ip_cmsg_recv_offset(msg, skb, 0, 0);
 }
 
 bool icmp_global_allow(void);

net/ipv4/ip_sockglue.c +6 -5

@@ -98,7 +98,7 @@ static void ip_cmsg_recv_retopts(struct
 }
 
 static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
-				  int offset)
+				  int tlen, int offset)
 {
 	__wsum csum = skb->csum;

@@ -106,8 +106,9 @@ static void ip_cmsg_recv_checksum(struct
 		return;
 
 	if (offset != 0)
-		csum = csum_sub(csum, csum_partial(skb_transport_header(skb),
-						   offset, 0));
+		csum = csum_sub(csum,
+				csum_partial(skb_transport_header(skb) + tlen,
+					     offset, 0));
 
 	put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum);
 }

@@ -153,7 +154,7 @@ static void ip_cmsg_recv_dstaddr(struct
 }
 
 void ip_cmsg_recv_offset(struct msghdr *msg, struct sk_buff *skb,
-			 int offset)
+			 int tlen, int offset)
 {
 	struct inet_sock *inet = inet_sk(skb->sk);
 	unsigned int flags = inet->cmsg_flags;

@@ -216,7 +217,7 @@ void ip_cmsg_recv_offset(struct msghdr *
 	}
 
 	if (flags & IP_CMSG_CHECKSUM)
-		ip_cmsg_recv_checksum(msg, skb, offset);
+		ip_cmsg_recv_checksum(msg, skb, tlen, offset);
 }
 EXPORT_SYMBOL(ip_cmsg_recv_offset);

net/ipv4/udp.c +1 -1

@@ -1327,7 +1327,7 @@ try_again:
 		*addr_len = sizeof(*sin);
 	}
 	if (inet->cmsg_flags)
-		ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr) + off);
+		ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr), off);
 
 	err = copied;
 	if (flags & MSG_TRUNC)

net/ipv6/udp.c +2 -1

@@ -427,7 +427,8 @@ try_again:
 
 	if (is_udp4) {
 		if (inet->cmsg_flags)
-			ip_cmsg_recv(msg, skb);
+			ip_cmsg_recv_offset(msg, skb,
+					    sizeof(struct udphdr), off);
 	} else {
 		if (np->rxopt.all)
 			ip6_datagram_recv_specific_ctl(sk, msg, skb);

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/ipv4-use-the-right-lock-for-ping_group_range.patch queue-4.8/ipv4-disable-bh-in-set_ping_group_range.patch queue-4.8/udp-fix-ip_checksum-handling.patch queue-4.8/netlink-do-not-enter-direct-reclaim-from-netlink_dump.patch queue-4.8/ipv6-tcp-restore-ip6cb-for-pktoptions-skbs.patch queue-4.8/packet-on-direct_xmit-limit-tso-and-csum-to-supported-devices.patch queue-4.8/net-pktgen-remove-rcu-locking-in-pktgen_change_name.patch