Re: [PATCH v2] drivers/misc/vmw_vmci: restrict too big queue size in

[Alex Dewar]

On 09/02/2021 09:31, Sabyrzhan Tasbolatov wrote:
> syzbot found WARNING in qp_broker_alloc[1] in qp_host_alloc_queue()
> when num_pages is 0x100001, giving queue_size + queue_page_size
> bigger than KMALLOC_MAX_SIZE for kzalloc(), resulting order >= MAX_ORDER
> condition.
>
> queue_size + queue_page_size=0x8000d8, where KMALLOC_MAX_SIZE=0x400000.
>
> Reported-by: syzbot+15ec7391f3d6a1a7cc7d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@xxxxxxxxx>
> ---
> > As this is controllable by userspace, you just provided a way to flood
> > the kernel logs.
> >
> > Please make this a dev_dbg() call instead, if you really want to see it.
> > Otherwise just return NULL, no need to report anything, right?
> Thanks, removed pr_warn().
Looks like you forgot to take out the opening brace.

> v2: Removed pr_warn() to avoid flood from user-space
> ---
>   drivers/misc/vmw_vmci/vmci_queue_pair.c | 2 --
>   1 file changed, 2 deletions(-)
>
> diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
> index f6af406fda80..ea16df73cde0 100644
> --- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
> +++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
> @@ -538,9 +538,7 @@ static struct vmci_queue *qp_host_alloc_queue(u64 size)
>   	queue_page_size = num_pages * sizeof(*queue->kernel_if->u.h.page);
>   
>   	if (queue_size + queue_page_size > KMALLOC_MAX_SIZE) {
> -		pr_warn("too big queue to allocate\n");
>   		return NULL;
> -	}
>   
>   	queue = kzalloc(queue_size + queue_page_size, GFP_KERNEL);
>   	if (queue) {