[Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[P J P]

From: Prasad J Pandit <pjp@fedoraproject.org>

virtio back end uses set of buffers to facilitate I/O operations.
If its size is too large, 'cpu_physical_memory_map' could return
a null address. This would result in a null dereference while
un-mapping descriptors. Add check to avoid it.

Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/virtio/virtio.c | 5 +++++
 1 file changed, 5 insertions(+)

Update per:
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 15ee3a7..311dd0b 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
         }
 
         iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
+        if (!iov[num_sg].iov_base) {
+            error_report("virtio: bogus descriptor or out of resources");
+            exit(EXIT_FAILURE);
+        }
+
         iov[num_sg].iov_len = len;
         addr[num_sg] = pa;
 
-- 
2.5.5

Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Laszlo Ersek]

On 09/19/16 11:06, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
> 
> virtio back end uses set of buffers to facilitate I/O operations.
> If its size is too large, 'cpu_physical_memory_map' could return
> a null address. This would result in a null dereference while
> un-mapping descriptors. Add check to avoid it.
> 
> Reported-by: Qinghao Tang <luodalongde@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/virtio/virtio.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> Update per:
>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 15ee3a7..311dd0b 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
>          }
>  
>          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
> +        if (!iov[num_sg].iov_base) {
> +            error_report("virtio: bogus descriptor or out of resources");
> +            exit(EXIT_FAILURE);
> +        }
> +
>          iov[num_sg].iov_len = len;
>          addr[num_sg] = pa;
>  
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 1322 bytes --]

On Mon, Sep 19, 2016 at 02:36:11PM +0530, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
> 
> virtio back end uses set of buffers to facilitate I/O operations.
> If its size is too large, 'cpu_physical_memory_map' could return
> a null address. This would result in a null dereference while
> un-mapping descriptors. Add check to avoid it.
> 
> Reported-by: Qinghao Tang <luodalongde@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/virtio/virtio.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> Update per:
>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 15ee3a7..311dd0b 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
>          }
>  
>          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
> +        if (!iov[num_sg].iov_base) {
> +            error_report("virtio: bogus descriptor or out of resources");
> +            exit(EXIT_FAILURE);

exit(1) is used everywhere else in the file (including just a few lines
above in the same function).  Please use exit(1) for consistency.

Looks fine otherwise.

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Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Laszlo Ersek]

On 09/19/16 17:55, Stefan Hajnoczi wrote:
> On Mon, Sep 19, 2016 at 02:36:11PM +0530, P J P wrote:
>> From: Prasad J Pandit <pjp@fedoraproject.org>
>>
>> virtio back end uses set of buffers to facilitate I/O operations.
>> If its size is too large, 'cpu_physical_memory_map' could return
>> a null address. This would result in a null dereference while
>> un-mapping descriptors. Add check to avoid it.
>>
>> Reported-by: Qinghao Tang <luodalongde@gmail.com>
>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>> ---
>>  hw/virtio/virtio.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> Update per:
>>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html
>>
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 15ee3a7..311dd0b 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
>>          }
>>  
>>          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
>> +        if (!iov[num_sg].iov_base) {
>> +            error_report("virtio: bogus descriptor or out of resources");
>> +            exit(EXIT_FAILURE);
> 
> exit(1) is used everywhere else in the file (including just a few lines
> above in the same function).  Please use exit(1) for consistency.

Laurent's pending series

[Qemu-devel] [PATCH 00/26] trivial: use exit(EXIT_SUCCESS) and
                           exit(EXIT_FAILURE)

specifically his patch

[Qemu-devel] [PATCH 11/26] pci, virtio: use exit(EXIT_SUCCESS) and
                           exit(EXIT_FAILURE)

converts the argument of the exit() that you name to EXIT_FAILURE.

So using EXIT_FAILURE in Prasad's patch is actually what will uphold
consistency.

> Looks fine otherwise.
> 

Thanks!
Laszlo

Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Laurent Vivier]

On 19/09/2016 18:59, Laszlo Ersek wrote:
> On 09/19/16 17:55, Stefan Hajnoczi wrote:
>> On Mon, Sep 19, 2016 at 02:36:11PM +0530, P J P wrote:
>>> From: Prasad J Pandit <pjp@fedoraproject.org>
>>>
>>> virtio back end uses set of buffers to facilitate I/O operations.
>>> If its size is too large, 'cpu_physical_memory_map' could return
>>> a null address. This would result in a null dereference while
>>> un-mapping descriptors. Add check to avoid it.
>>>
>>> Reported-by: Qinghao Tang <luodalongde@gmail.com>
>>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>>> ---
>>>  hw/virtio/virtio.c | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> Update per:
>>>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html
>>>
>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>> index 15ee3a7..311dd0b 100644
>>> --- a/hw/virtio/virtio.c
>>> +++ b/hw/virtio/virtio.c
>>> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
>>>          }
>>>  
>>>          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
>>> +        if (!iov[num_sg].iov_base) {
>>> +            error_report("virtio: bogus descriptor or out of resources");
>>> +            exit(EXIT_FAILURE);
>>
>> exit(1) is used everywhere else in the file (including just a few lines
>> above in the same function).  Please use exit(1) for consistency.
> 
> Laurent's pending series
> 
> [Qemu-devel] [PATCH 00/26] trivial: use exit(EXIT_SUCCESS) and
>                            exit(EXIT_FAILURE)
> 
> specifically his patch
> 
> [Qemu-devel] [PATCH 11/26] pci, virtio: use exit(EXIT_SUCCESS) and
>                            exit(EXIT_FAILURE)
> 
> converts the argument of the exit() that you name to EXIT_FAILURE.
> 
> So using EXIT_FAILURE in Prasad's patch is actually what will uphold
> consistency.
> 
>> Looks fine otherwise.
>>

Laszlo, it seems Peter (and some others) would prefer to use exit(1)
instead of exit(EXIT_FAILURE), so I don't think my series will be applied.

Laurent

Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[Laszlo Ersek]

On 09/19/16 19:16, Laurent Vivier wrote:
> 
> 
> On 19/09/2016 18:59, Laszlo Ersek wrote:
>> On 09/19/16 17:55, Stefan Hajnoczi wrote:
>>> On Mon, Sep 19, 2016 at 02:36:11PM +0530, P J P wrote:
>>>> From: Prasad J Pandit <pjp@fedoraproject.org>
>>>>
>>>> virtio back end uses set of buffers to facilitate I/O operations.
>>>> If its size is too large, 'cpu_physical_memory_map' could return
>>>> a null address. This would result in a null dereference while
>>>> un-mapping descriptors. Add check to avoid it.
>>>>
>>>> Reported-by: Qinghao Tang <luodalongde@gmail.com>
>>>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>>>> ---
>>>>  hw/virtio/virtio.c | 5 +++++
>>>>  1 file changed, 5 insertions(+)
>>>>
>>>> Update per:
>>>>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html
>>>>
>>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>>> index 15ee3a7..311dd0b 100644
>>>> --- a/hw/virtio/virtio.c
>>>> +++ b/hw/virtio/virtio.c
>>>> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
>>>>          }
>>>>  
>>>>          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
>>>> +        if (!iov[num_sg].iov_base) {
>>>> +            error_report("virtio: bogus descriptor or out of resources");
>>>> +            exit(EXIT_FAILURE);
>>>
>>> exit(1) is used everywhere else in the file (including just a few lines
>>> above in the same function).  Please use exit(1) for consistency.
>>
>> Laurent's pending series
>>
>> [Qemu-devel] [PATCH 00/26] trivial: use exit(EXIT_SUCCESS) and
>>                            exit(EXIT_FAILURE)
>>
>> specifically his patch
>>
>> [Qemu-devel] [PATCH 11/26] pci, virtio: use exit(EXIT_SUCCESS) and
>>                            exit(EXIT_FAILURE)
>>
>> converts the argument of the exit() that you name to EXIT_FAILURE.
>>
>> So using EXIT_FAILURE in Prasad's patch is actually what will uphold
>> consistency.
>>
>>> Looks fine otherwise.
>>>
> 
> Laszlo, it seems Peter (and some others) would prefer to use exit(1)
> instead of exit(EXIT_FAILURE), so I don't think my series will be applied.

Thanks for the information, Laurent!

Prasad, can you please send a v3 then, to address Stefan's feedback?

Thank you
Laszlo

Re: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address

[P J P]

+-- On Mon, 19 Sep 2016, Laszlo Ersek wrote --+
| Prasad, can you please send a v3 then, to address Stefan's feedback?

Yes, sent patch v3. Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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