Re: [Qemu-devel] net: vmxnet3: memory leakage issue

[Dmitry Fleytman <dmitry@daynix.com>]

Sent from my iPhone

> On 11 Dec 2015, at 11:10, Jason Wang <jasowang@redhat.com> wrote:
> 
> 
> 
>> On 12/09/2015 11:28 PM, P J P wrote:
>>   Hello Jason, Dmitry,
>> 
>> +-- On Tue, 8 Dec 2015, P J P wrote --+
>> | |1) VMXNET3_CMD_QUIESCE_DEV
>> | 
>> |   IIUC, it is used to pause the device when the receiver end is unable to 
>> | keee-up with the incoming flow. After a brief period, the operation could be 
>> | resumed again.
>> | 
>> | |2) VMXNET3_REG_DSAL
>> | 
>> |    Shared memory between a driver and the device appears to be set in two 
>> | steps. Firs low address, followed by the high address(VMXNET3_REG_DSAH). I 
>> | guess 's->device_active' needs to be enabled again while setting the higher 
>> | part of the address.
>> 
>> Please see below another (tested)patch, it fixes the VMXNET3_CMD_QUIESCE_DEV 
>> case above. It's not clear if the device would be initialised and active while 
>> setting shared memory via VMXNET3_REG_DSAL/DSAH.
> 
> I think it's possible for attacker. Better wait for Dmitry's answer for
> this.

Hi Guys,

I'd like to review this carefully. I'll post my thoughts tomorrow or on Sunday.

Thanks,
Dmitry


> 
>> 
>> ===
>> From 81c4ecb67635435f01397dc21210497e6420bdca Mon Sep 17 00:00:00 2001
>> From: Prasad J Pandit <pjp@fedoraproject.org>
>> Date: Wed, 9 Dec 2015 20:45:25 +0530
>> Subject: [PATCH] net: vmxnet3: avoid memory leakage in activate_device
>> 
>> Vmxnet3 device emulator does not check if the device is active
>> before activating it, resulting in memory leakage on the host.
>> This memory leakage could also occur, if the device was paused
>> during flow control and activated thereafter.
>> 
>> Introduced a 'Pause' state for the vmxnet3 device to differentiate
>> it from the earlier active and inactive states. One need not
>> 'activate' the device to resume operation after pause.
>> 
>> This patch adds a check to verify these device states and avoid
>> memory leakage during activating the device.
>> 
>> Reported-by: Qinghao Tang <luodalongde@gmail.com>
>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>> ---
>> hw/net/vmxnet3.c | 43 +++++++++++++++++++++++++++++++++++--------
>> hw/net/vmxnet3.h |  6 ++++++
>> 2 files changed, 41 insertions(+), 8 deletions(-)
>> 
>> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
>> index 37373e5..be2c9e2 100644
>> --- a/hw/net/vmxnet3.c
>> +++ b/hw/net/vmxnet3.c
>> @@ -1195,7 +1195,19 @@ static void vmxnet3_reset_mac(VMXNET3State *s)
>> static void vmxnet3_deactivate_device(VMXNET3State *s)
>> {
>>     VMW_CBPRN("Deactivating vmxnet3...");
>> -    s->device_active = false;
>> +    s->device_active = VMXNET3_DEV_DEACTIVE;
>> +}
>> +
>> +static void vmxnet3_pause_device(VMXNET3State *s)
>> +{
>> +    VMW_CBPRN("Pausing vmxnet3...");
>> +    s->device_active = VMXNET3_DEV_PAUSE;
>> +}
>> +
>> +static void vmxnet3_resume_device(VMXNET3State *s)
>> +{
>> +    VMW_CBPRN("Resuming vmxnet3...");
>> +    s->device_active = VMXNET3_DEV_ACTIVE;
>> }
>> 
>> static void vmxnet3_reset(VMXNET3State *s)
>> @@ -1431,6 +1443,12 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>         return;
>>     }
>> 
>> +    /* Verify if device is active */
>> +    if (s->device_active) {
>> +        VMW_CFPRN("Vmxnet3 device is active");
>> +        return;
>> +    }
> 
> What if guest want to activate a paused device?
> 
>> +
>>     vmxnet3_adjust_by_guest_type(s);
>>     vmxnet3_update_features(s);
>>     vmxnet3_update_pm_state(s);
>> @@ -1566,7 +1584,7 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>> 
>>     vmxnet3_reset_mac(s);
>> 
>> -    s->device_active = true;
>> +    s->device_active = VMXNET3_DEV_ACTIVE;
>> }
>> 
>> static void vmxnet3_handle_command(VMXNET3State *s, uint64_t cmd)
>> @@ -1627,8 +1645,13 @@ static void vmxnet3_handle_command(VMXNET3State *s, uint64_t cmd)
>>         break;
>> 
>>     case VMXNET3_CMD_QUIESCE_DEV:
>> -        VMW_CBPRN("Set: VMXNET3_CMD_QUIESCE_DEV - pause the device");
>> -        vmxnet3_deactivate_device(s);
>> +        if (s->device_active & VMXNET3_DEV_ACTIVE) {
>> +            VMW_CBPRN("Set: VMXNET3_CMD_QUIESCE_DEV - pause the device");
>> +            vmxnet3_pause_device(s);
>> +        } else if (s->device_active & VMXNET3_DEV_PAUSE) {
>> +            VMW_CBPRN("Set: VMXNET3_CMD_QUIESCE_DEV - resume the device");
>> +            vmxnet3_resume_device(s);
>> +        }
> 
> Not sure this is the correct behavior. Is there a link to the spec?
> 
>>         break;
>> 
>>     case VMXNET3_CMD_GET_CONF_INTR:
>> @@ -1652,12 +1675,16 @@ static uint64_t vmxnet3_get_command_status(VMXNET3State *s)
>> 
>>     switch (s->last_command) {
>>     case VMXNET3_CMD_ACTIVATE_DEV:
>> -        ret = (s->device_active) ? 0 : -1;
>> +        ret = (s->device_active & VMXNET3_DEV_ACTIVE) ? 0 : -1;
>>         VMW_CFPRN("Device active: %" PRIx64, ret);
>>         break;
>> 
>> -    case VMXNET3_CMD_RESET_DEV:
>>     case VMXNET3_CMD_QUIESCE_DEV:
>> +        ret = (s->device_active & VMXNET3_DEV_PAUSE) ? 0 : -1;
>> +        VMW_CFPRN("Device pause: %" PRIx64, ret);
>> +        break;
>> +
>> +    case VMXNET3_CMD_RESET_DEV:
>>     case VMXNET3_CMD_GET_QUEUE_STATUS:
>>         ret = 0;
>>         break;
>> @@ -1741,7 +1768,7 @@ vmxnet3_io_bar1_write(void *opaque,
>>          * shared address only after we get the high part
>>          */
>>         if (val == 0) {
>> -            s->device_active = false;
>> +            s->device_active = VMXNET3_DEV_DEACTIVE;
>>         }
>>         s->temp_shared_guest_driver_memory = val;
>>         s->drv_shmem = 0;
>> @@ -1863,7 +1890,7 @@ static int
>> vmxnet3_can_receive(NetClientState *nc)
>> {
>>     VMXNET3State *s = qemu_get_nic_opaque(nc);
>> -    return s->device_active &&
>> +    return (s->device_active & VMXNET3_DEV_ACTIVE) &&
>>            VMXNET_FLAG_IS_SET(s->link_status_and_speed, VMXNET3_LINK_STATUS_UP);
>> }
>> 
>> diff --git a/hw/net/vmxnet3.h b/hw/net/vmxnet3.h
>> index f7006af..71a7861 100644
>> --- a/hw/net/vmxnet3.h
>> +++ b/hw/net/vmxnet3.h
>> @@ -202,6 +202,12 @@ enum {
>>     VMXNET3_CMD_GET_ADAPTIVE_RING_INFO                    /* 0xF00D0009 */
>> };
>> 
>> +enum {
>> +    VMXNET3_DEV_DEACTIVE = 0x00,  /* device deactive */
>> +    VMXNET3_DEV_ACTIVE = 0x01,    /* device active  */
>> +    VMXNET3_DEV_PAUSE = 0x02      /* device pause */
>> +};
>> +
>> /* Adaptive Ring Info Flags */
>> #define VMXNET3_DISABLE_ADAPTIVE_RING 1
>