linux-kernel - [PATCH] vhost: zero vhost_vsock memory on allocation

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Date:   Tue, 26 Mar 2019 20:56:14 -0400
From:   Vitaly Mayatskikh <v.mayatskih@...il.com>
To:     Stefan Hajnoczi <stefanha@...hat.com>
Cc:     Michal Hocko <mhocko@...e.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] vhost: zero vhost_vsock memory on allocation

This fixes OOPS when using under-initialized vhost_vsock object.

The code had a combo of kzalloc plus vmalloc as a fallback
initially, but it has been replaced by plain kvmalloc in
commit 6c5ab6511f71 ("mm: support __GFP_REPEAT in kvmalloc_node for >32kB")

OOPS is easy to reproduce with open/ioctl after trashing the RAM.

Signed-off-by: Vitaly Mayatskikh <v.mayatskih@...il.com>
---
 drivers/vhost/vsock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index bb5fc0e..9e7cb13 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -512,7 +512,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 	/* This struct is large and allocation could fail, fall back to vmalloc
 	 * if there is no other way.
 	 */
-	vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	vsock = kvzalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 	if (!vsock)
 		return -ENOMEM;
 
-- 
1.8.3.1