[PATCH net] ipv4: fix memory leaks in ip_cmsg_send() callers

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

Dmitry reported memory leaks of IP options allocated in
ip_cmsg_send() when/if this function returns an error.

Callers are responsible for the freeing.

Many thanks to Dmitry for the report and diagnostic.

Reported-by: Dmitry Vyukov <dvyu...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/ipv4/ip_sockglue.c |    2 ++
 net/ipv4/ping.c        |    4 +++-
 net/ipv4/raw.c         |    4 +++-
 net/ipv4/udp.c         |    4 +++-
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 5f73a7c03e27..a50124260f5a 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -249,6 +249,8 @@ int ip_cmsg_send(struct net *net, struct msghdr *msg, 
struct ipcm_cookie *ipc,
                switch (cmsg->cmsg_type) {
                case IP_RETOPTS:
                        err = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct 
cmsghdr));
+
+                       /* Our caller is responsible for freeing ipc->opt */
                        err = ip_options_get(net, &ipc->opt, CMSG_DATA(cmsg),
                                             err < 40 ? err : 40);
                        if (err)
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index c117b21b937d..ec74b1a34315 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -746,8 +746,10 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr 
*msg, size_t len)
 
        if (msg->msg_controllen) {
                err = ip_cmsg_send(sock_net(sk), msg, &ipc, false);
-               if (err)
+               if (unlikely(err)) {
+                       kfree(ipc.opt);
                        return err;
+               }
                if (ipc.opt)
                        free = 1;
        }
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index bc35f1842512..bba4f6f379a9 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -547,8 +547,10 @@ static int raw_sendmsg(struct sock *sk, struct msghdr 
*msg, size_t len)
 
        if (msg->msg_controllen) {
                err = ip_cmsg_send(net, msg, &ipc, false);
-               if (err)
+               if (unlikely(err)) {
+                       kfree(ipc.opt);
                        goto out;
+               }
                if (ipc.opt)
                        free = 1;
        }
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index be0b21852b13..8182363bff5e 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1048,8 +1048,10 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, 
size_t len)
        if (msg->msg_controllen) {
                err = ip_cmsg_send(sock_net(sk), msg, &ipc,
                                   sk->sk_family == AF_INET6);
-               if (err)
+               if (unlikely(err)) {
+                       kfree(ipc.opt);
                        return err;
+               }
                if (ipc.opt)
                        free = 1;
                connected = 0;