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

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Message-ID: <a10296cf-4545-c7f3-1d3c-31fbd05c3f6c@gmail.com>
Date:   Tue, 9 Feb 2021 09:32:04 +0000
From:   Alex Dewar <alex.dewar90@...il.com>
To:     Sabyrzhan Tasbolatov <snovitoll@...il.com>,
        gregkh@...uxfoundation.org
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org,
        syzbot+15ec7391f3d6a1a7cc7d@...kaller.appspotmail.com
Subject: Re: [PATCH v2] drivers/misc/vmw_vmci: restrict too big queue size in

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@...kaller.appspotmail.com
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
> ---
>> 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) {