[PATCH 5.10.y-6.18.y] s390/vmcp: Initialize full session info to zero

[Christian Borntraeger <borntraeger@linux.ibm.com>]

The cma_alloc bit as well as the response can contain old data.
cma_release will not free the kmalloced memory in that case and
the response code might leak kernel stack data to CAP_SYS_ADMIN
users.

Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
[borntraeger@linux.ibm.com: use kzalloc instead of kzalloc_obj for older versions]
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
---
 drivers/s390/char/vmcp.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c
index 69899bb86b3ef..1d07d7b6acb82 100644
--- a/drivers/s390/char/vmcp.c
+++ b/drivers/s390/char/vmcp.c
@@ -105,13 +105,11 @@ static int vmcp_open(struct inode *inode, struct file *file)
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	session = kmalloc(sizeof(*session), GFP_KERNEL);
+	session = kzalloc(sizeof(*session), GFP_KERNEL);
 	if (!session)
 		return -ENOMEM;
 
 	session->bufsize = PAGE_SIZE;
-	session->response = NULL;
-	session->resp_size = 0;
 	mutex_init(&session->mutex);
 	file->private_data = session;
 	return nonseekable_open(inode, file);
-- 
2.53.0