--- /dev/null
+From zhengjunling@huawei.com Tue Jun 2 15:26:33 2015
+From: Junling Zheng <zhengjunling@huawei.com>
+Date: Mon, 1 Jun 2015 09:28:00 +0000
+Subject: net: socket: Fix the wrong returns for recvmsg and sendmsg
+To: <gregkh@linuxfoundation.org>
+Cc: <lizefan@huawei.com>, <viro@zeniv.linux.org.uk>, <davem@davemloft.net>, <xuhanbing@huawei.com>, <stable@vger.kernel.org>, <netdev@vger.kernel.org>
+Message-ID: <1433150880-9976-1-git-send-email-zhengjunling@huawei.com>
+
+From: Junling Zheng <zhengjunling@huawei.com>
+
+Based on 08adb7dabd4874cc5666b4490653b26534702ce0 upstream.
+
+We found that after v3.10.73, recvmsg might return -EFAULT while -EINVAL
+was expected.
+
+We tested it through the recvmsg01 testcase come from LTP testsuit. It set
+msg->msg_namelen to -1 and the recvmsg syscall returned errno 14, which is
+unexpected (errno 22 is expected):
+
+recvmsg01 4 TFAIL : invalid socket length ; returned -1 (expected -1),
+errno 14 (expected 22)
+
+Linux mainline has no this bug for commit 08adb7dab fixes it accidentally.
+However, it is too large and complex to be backported to LTS 3.10.
+
+Commit 281c9c36 (net: compat: Update get_compat_msghdr() to match
+copy_msghdr_from_user() behaviour) made get_compat_msghdr() return
+error if msg_sys->msg_namelen was negative, which changed the behaviors
+of recvmsg and sendmsg syscall in a lib32 system:
+
+Before commit 281c9c36, get_compat_msghdr() wouldn't fail and it would
+return -EINVAL in move_addr_to_user() or somewhere if msg_sys->msg_namelen
+was invalid and then syscall returned -EINVAL, which is correct.
+
+And now, when msg_sys->msg_namelen is negative, get_compat_msghdr() will
+fail and wants to return -EINVAL, however, the outer syscall will return
+-EFAULT directly, which is unexpected.
+
+This patch gets the return value of get_compat_msghdr() as well as
+copy_msghdr_from_user(), then returns this expected value if
+get_compat_msghdr() fails.
+
+Fixes: 281c9c36 (net: compat: Update get_compat_msghdr() to match copy_msghdr_from_user() behaviour)
+Signed-off-by: Junling Zheng <zhengjunling@huawei.com>
+Signed-off-by: Hanbing Xu <xuhanbing@huawei.com>
+Cc: Li Zefan <lizefan@huawei.com>
+Cc: Al Viro <viro@zeniv.linux.org.uk>
+Cc: David Miller <davem@davemloft.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ net/socket.c | 24 ++++++++++--------------
+ 1 file changed, 10 insertions(+), 14 deletions(-)
+
+--- a/net/socket.c
++++ b/net/socket.c
+@@ -2007,14 +2007,12 @@ static int ___sys_sendmsg(struct socket
+ int err, ctl_len, total_len;
+
+ err = -EFAULT;
+- if (MSG_CMSG_COMPAT & flags) {
+- if (get_compat_msghdr(msg_sys, msg_compat))
+- return -EFAULT;
+- } else {
++ if (MSG_CMSG_COMPAT & flags)
++ err = get_compat_msghdr(msg_sys, msg_compat);
++ else
+ err = copy_msghdr_from_user(msg_sys, msg);
+- if (err)
+- return err;
+- }
++ if (err)
++ return err;
+
+ if (msg_sys->msg_iovlen > UIO_FASTIOV) {
+ err = -EMSGSIZE;
+@@ -2219,14 +2217,12 @@ static int ___sys_recvmsg(struct socket
+ struct sockaddr __user *uaddr;
+ int __user *uaddr_len;
+
+- if (MSG_CMSG_COMPAT & flags) {
+- if (get_compat_msghdr(msg_sys, msg_compat))
+- return -EFAULT;
+- } else {
++ if (MSG_CMSG_COMPAT & flags)
++ err = get_compat_msghdr(msg_sys, msg_compat);
++ else
+ err = copy_msghdr_from_user(msg_sys, msg);
+- if (err)
+- return err;
+- }
++ if (err)
++ return err;
+
+ if (msg_sys->msg_iovlen > UIO_FASTIOV) {
+ err = -EMSGSIZE;