Re: [Qemu-devel] [PATCH v3 6/7] memory-device: avoid overflows on very huge devices

From: David Gibson <david@gibson.dropbear.id.au>
To: David Hildenbrand <david@redhat.com>
Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" <mst@redhat.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	Michael Roth <mdroth@linux.vnet.ibm.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v3 6/7] memory-device: avoid overflows on very huge devices
Date: Thu, 25 Oct 2018 15:44:37 +0100	[thread overview]
Message-ID: <20181025144436.GE2697@umbus.hotspot.internet-for-guests.com> (raw)
In-Reply-To: <20181023152306.3123-7-david@redhat.com>

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On Tue, Oct 23, 2018 at 05:23:05PM +0200, David Hildenbrand wrote:
> Should not be a problem right now, but it could theoretically happen
> in the future.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/mem/memory-device.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
> index 996ad1490f..8be63c8032 100644
> --- a/hw/mem/memory-device.c
> +++ b/hw/mem/memory-device.c
> @@ -85,7 +85,8 @@ static void memory_device_check_addable(MachineState *ms, uint64_t size,
>  
>      /* will we exceed the total amount of memory specified */
>      memory_device_used_region_size(OBJECT(ms), &used_region_size);
> -    if (used_region_size + size > ms->maxram_size - ms->ram_size) {
> +    if (used_region_size + size < used_region_size ||
> +        used_region_size + size > ms->maxram_size - ms->ram_size) {
>          error_setg(errp, "not enough space, currently 0x%" PRIx64
>                     " in use of total space for memory devices 0x" RAM_ADDR_FMT,
>                     used_region_size, ms->maxram_size - ms->ram_size);

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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