[PATCH 4.4 021/115] net: initialize msg.msg_flags in recvfrom

Greg Kroah-Hartman
2017-12-18T18:12:10Z

From: Alexander Potapenko <glider@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 <glider@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/socket.c | 1 +
1 file changed, 1 insertion(+)

--- a/net/socket.c
+++ b/net/socket.c
@@ -1697,6 +1697,7 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void
/* 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, iov_iter_count(&msg.msg_iter), flags);