Re: [Qemu-devel] [PATCH v3 29/46] ivshmem: error on too many eventfd received

[Claudio Fontana]

On 15.09.2015 18:07, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
> 
> The number of eventfd that can be handled per peer is limited by the
> number of vectors. Return an error when receiving too many of them.
> 
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  hw/misc/ivshmem.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index b9c78cd..63e4c4f 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -569,6 +569,13 @@ static void ivshmem_read(void *opaque, const uint8_t 
> *buf, int size)
>      }
>  
>      /* get a new eventfd */
> +    if (peer->nb_eventfds >= s->vectors) {
> +        error_report("Too many eventfd received, device has %d vectors",
> +                     s->vectors);
> +        close(incoming_fd);
> +        return;
> +    }
> +
>      nth_eventfd = peer->nb_eventfds++;
>  
>      /* this is an eventfd for a particular peer VM */
> 

can the device still operate if we detect these errors at ivshmem_read time?

I am referring also to the other checks happening in ivshmem_read doing

if ([something fails]) {
    error_report("abcabc");
    /* close(), ... */
    return;
}

Can the device stop operating if these conditions happen?
If so, do we have to put the device into a non-operating state, where all 
read/writes are ignored? Should there be a ivshmem status flag for ERROR?
Should we exit(1)?

note: I don't know what the "proper" behavior should be, but I am concerned 
about the runtime stability of the software which uses the device.


Ciao,

Claudio