linux-kernel - Re: [PATCH virt] virt: fix uninit-value in vhost_vsock_dev

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Date: Sat, 20 Apr 2024 06:05:15 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Jeongjun Park <aha310510@...il.com>
Cc: syzbot+6c21aeb59d0e82eb2782@...kaller.appspotmail.com,
	stefanha@...hat.com, sgarzare@...hat.com, jasowang@...hat.com,
	kvm@...r.kernel.org, virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH virt] virt: fix uninit-value in vhost_vsock_dev_open

On Sat, Apr 20, 2024 at 05:57:50PM +0900, Jeongjun Park wrote:
> Change vhost_vsock_dev_open() to use kvzalloc() instead of kvmalloc()
> to avoid uninit state.
> 
> Reported-by: syzbot+6c21aeb59d0e82eb2782@...kaller.appspotmail.com
> Fixes: dcda9b04713c ("mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic")
> Signed-off-by: Jeongjun Park <aha310510@...il.com>

What value exactly is used uninitialized?

> ---
>  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 ec20ecff85c7..652ef97a444b 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -656,7 +656,7 @@ 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;
>  
> -- 
> 2.34.1