Re: [Xen-devel] [PATCH] xen: fix potential integer overflow in queue_reply

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 18/01/16 16:29, Insu Yun wrote:
> When len is greater than UINT_MAX - sizeof(*rb), in next allocation,
> it can overflow integer range and allocates small size of heap.
> After that, memcpy will overflow the allocated heap.
> Therefore, it needs to check the size of given length.
[...]
> --- a/drivers/xen/xenbus/xenbus_dev_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
> @@ -186,7 +186,7 @@ static int queue_reply(struct list_head *queue, const 
> void *data, size_t len)
>  {
>       struct read_buffer *rb;
>  
> -     if (len == 0)
> +     if (len == 0 || len >= UINT_MAX - sizeof(*rb))
                               ^^^^^^^^^^^^^^^^^^^^^^
Please check

    len > XENSTORE_PAYLOAD_MAX

instead.

David

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