smb: client: allocate struct sess_data on the stack

CIFS_SessSetup() kzalloc()s struct sess_data only to run a synchronous
state machine and free it before returning; the object never escapes the
function.  At 96 bytes it fits comfortably on the stack even under
CONFIG_FRAME_WARN=1024, so drop the allocation and its failure path.

memzero_explicit() preserves the kfree_sensitive() scrubbing.

Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>

1 files changed, 12 insertions, 15 deletions

diff --git a/fs/smb/client/smb1session.c b/fs/smb/client/smb1session.c
index c45d3254dfac..5f469b4d70f7 100644
--- a/fs/smb/client/smb1session.c
+++ b/fs/smb/client/smb1session.c
@@ -949,34 +949,31 @@ static int select_sec(struct sess_data *sess_data)
 int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
 		   struct TCP_Server_Info *server)
 {
+	struct sess_data sess_data;
 	int rc = 0;
-	struct sess_data *sess_data;
 
 	if (ses == NULL) {
 		WARN(1, "%s: ses == NULL!", __func__);
 		return -EINVAL;
 	}
 
-	sess_data = kzalloc_obj(struct sess_data);
-	if (!sess_data)
-		return -ENOMEM;
+	sess_data = (struct sess_data) {
+		.xid		= xid,
+		.ses		= ses,
+		.server		= server,
+		.buf0_type	= CIFS_NO_BUFFER,
+	};
 
-	sess_data->xid = xid;
-	sess_data->ses = ses;
-	sess_data->server = server;
-	sess_data->buf0_type = CIFS_NO_BUFFER;
-
-	rc = select_sec(sess_data);
+	rc = select_sec(&sess_data);
 	if (rc)
 		goto out;
 
-	while (sess_data->func)
-		sess_data->func(sess_data);
+	while (sess_data.func)
+		sess_data.func(&sess_data);
 
-	/* Store result before we free sess_data */
-	rc = sess_data->result;
+	rc = sess_data.result;
 
 out:
-	kfree_sensitive(sess_data);
+	memzero_explicit(&sess_data, sizeof(sess_data));
 	return rc;
 }