[PATCH AUTOSEL for 4.9 007/156] net: initialize msg.msg_flags in recvfrom

[alexander . levin]

From: Alexander Potapenko <gli...@google.com>

[ Upstream commit 9f138fa609c47403374a862a08a41394be53d461 ]

KMSAN reports a use of uninitialized memory in put_cmsg() because
msg.msg_flags in recvfrom haven't been initialized properly.
The flag values don't affect the result on this path, but it's still a
good idea to initialize them explicitly.

Signed-off-by: Alexander Potapenko <gli...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
---
 net/socket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/socket.c b/net/socket.c
index 6bbccf05854f..05f13b24572c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1702,6 +1702,7 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, 
size_t, size,
        /* We assume all kernel code knows the size of sockaddr_storage */
        msg.msg_namelen = 0;
        msg.msg_iocb = NULL;
+       msg.msg_flags = 0;
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        err = sock_recvmsg(sock, &msg, flags);
-- 
2.11.0