[PATCH 5.19 24/38] cifs: always initialize struct msghdr smb_msg completely

Greg Kroah-Hartman
2022-09-21T15:51:59Z

From: Stefan Metzmacher <metze@samba.org>

commit bedc8f76b3539ac4f952114b316bcc2251e808ce upstream.

So far we were just lucky because the uninitialized members
of struct msghdr are not used by default on a SOCK_STREAM tcp
socket.

But as new things like msg_ubuf and sg_from_iter where added
recently, we should play on the safe side and avoid potention
problems in future.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Cc: stable@vger.kernel.org
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/connect.c | 11 +++--------
fs/cifs/transport.c | 6 +-----
2 files changed, 4 insertions(+), 13 deletions(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -707,9 +707,6 @@ cifs_readv_from_socket(struct TCP_Server
int length = 0;
int total_read;

- smb_msg->msg_control = NULL;
- smb_msg->msg_controllen = 0;
-
for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
try_to_freeze();

@@ -765,7 +762,7 @@ int
cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
unsigned int to_read)
{
- struct msghdr smb_msg;
+ struct msghdr smb_msg = {};
struct kvec iov = {.iov_base = buf, .iov_len = to_read};
iov_iter_kvec(&smb_msg.msg_iter, READ, &iov, 1, to_read);

@@ -775,15 +772,13 @@ cifs_read_from_socket(struct TCP_Server_
ssize_t
cifs_discard_from_socket(struct TCP_Server_Info *server, size_t to_read)
{
- struct msghdr smb_msg;
+ struct msghdr smb_msg = {};

/*
* iov_iter_discard already sets smb_msg.type and count and iov_offset
* and cifs_readv_from_socket sets msg_control and msg_controllen
* so little to initialize in struct msghdr
*/
- smb_msg.msg_name = NULL;
- smb_msg.msg_namelen = 0;
iov_iter_discard(&smb_msg.msg_iter, READ, to_read);

return cifs_readv_from_socket(server, &smb_msg);
@@ -793,7 +788,7 @@ int
cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
unsigned int page_offset, unsigned int to_read)
{
- struct msghdr smb_msg;
+ struct msghdr smb_msg = {};
struct bio_vec bv = {
.bv_page = page, .bv_len = to_read, .bv_offset = page_offset};
iov_iter_bvec(&smb_msg.msg_iter, READ, &bv, 1, to_read);
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -196,10 +196,6 @@ smb_send_kvec(struct TCP_Server_Info *se

*sent = 0;

- smb_msg->msg_name = NULL;
- smb_msg->msg_namelen = 0;
- smb_msg->msg_control = NULL;
- smb_msg->msg_controllen = 0;
if (server->noblocksnd)
smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
else
@@ -311,7 +307,7 @@ __smb_send_rqst(struct TCP_Server_Info *
sigset_t mask, oldmask;
size_t total_len = 0, sent, size;
struct socket *ssocket = server->ssocket;
- struct msghdr smb_msg;
+ struct msghdr smb_msg = {};
__be32 rfc1002_marker;

if (cifs_rdma_enabled(server)) {