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Re: [Qemu-devel] [PATCH v6 4/5] virtio: validate config_len on load
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH v6 4/5] virtio: validate config_len on load |
Date: |
Mon, 05 May 2014 16:22:53 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Juan Quintela <address@hidden> wrote:
> "Michael S. Tsirkin" <address@hidden> wrote:
>> Malformed input can have config_len in migration stream
>> exceed the array size allocated on destination, the
>> result will be heap overflow.
>>
>> To fix, that config_len matches on both sides.
>>
>> CVE-2014-0182
>>
>> Reported-by: "Dr. David Alan Gilbert" <address@hidden>
>> Signed-off-by: Michael S. Tsirkin <address@hidden>
>> ---
>> hw/virtio/virtio.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 3bad71e..0d5d368 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -898,6 +898,7 @@ int virtio_set_features(VirtIODevice *vdev, uint32_t val)
>> int virtio_load(VirtIODevice *vdev, QEMUFile *f)
>> {
>> int i, ret;
>> + int32_t config_len;
>
> Has a warning.
>
> /mnt/kvm/qemu/next/hw/virtio/virtio.c: In function ‘virtio_load’:
> /mnt/kvm/qemu/next/hw/virtio/virtio.c:931:22: error: format ‘%i’
> expects argument of type ‘int’, but argument 2 has type ‘size_t’
> [-Werror=format=]
> config_len, vdev->config_len);
> ^
>
> changing config_len to size_t.
After discussing with michael, left it as int32_t
>
>> uint32_t num;
>> uint32_t features;
>> uint32_t supported_features;
>> @@ -924,7 +925,12 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
>> features, supported_features);
>> return -1;
>> }
>> - vdev->config_len = qemu_get_be32(f);
>> + config_len = qemu_get_be32(f);
>> + if (config_len != vdev->config_len) {
>> + error_report("Unexpected config length 0x%x. Expected 0x%x",
>
> and this to:
>
> s/%x/%zx/
and use here "%ix .... %zx"
Later, Juan.
> Later, Juan.
>
>
>> + config_len, vdev->config_len);
>> + return -1;
>> + }
>> qemu_get_buffer(f, vdev->config, vdev->config_len);
>>
>> num = qemu_get_be32(f);