Re: [PATCH v3 5/6] libvhost-user: prevent over-running max RAM slots

[Philippe Mathieu-Daudé]

On 1/17/22 09:20, David Hildenbrand wrote:
> On 17.01.22 05:12, Raphael Norwitz wrote:
>> When VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS support was added to
>> libvhost-user, no guardrails were added to protect against QEMU
>> attempting to hot-add too many RAM slots to a VM with a libvhost-user
>> based backed attached.
>>
>> This change adds the missing error handling by introducing a check on
>> the number of RAM slots the device has available before proceeding to
>> process the VHOST_USER_ADD_MEM_REG message.
>>
>> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
>> Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
>> ---
>>  subprojects/libvhost-user/libvhost-user.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)

>> +    if (dev->nregions == VHOST_USER_MAX_RAM_SLOTS) {
>> +        close(vmsg->fds[0]);
>> +        vu_panic(dev, "failing attempt to hot add memory via "
>> +                      "VHOST_USER_ADD_MEM_REG message because the backend 
>> has "
>> +                      "no free ram slots available");
> 
> Maybe simply "VHOST_USER_ADD_MEM_REG failed because there are no free
> ram slots"
> 
> Reviewed-by: David Hildenbrand <david@redhat.com>
> 

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>