Re: [PATCH v2 1/3] Fixed assert in vhost_user_set_mem_table_postcopy

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 15, 2020 at 09:57:04PM -0500, Raphael Norwitz wrote:
> The current vhost_user_set_mem_table_postcopy() implementation
> populates each region of the VHOST_USER_SET_MEM_TABLE message without
> first checking if there are more than VHOST_MEMORY_MAX_NREGIONS already
> populated. This can cause memory corruption if too many regions are
> added to the message during the postcopy step.
> 
> This change moves an existing assert up such that attempting to
> construct a VHOST_USER_SET_MEM_TABLE message with too many memory
> regions will gracefully bring down qemu instead of corrupting memory.
> 
> Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
> Signed-off-by: Peter Turschmid <peter.turschm@nutanix.com>


Could you pls add Fixes: and stable tags?

> ---
>  hw/virtio/vhost-user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 2e81f55..cce851a 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -443,6 +443,7 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
>                                       &offset);
>          fd = memory_region_get_fd(mr);
>          if (fd > 0) {
> +            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
>              trace_vhost_user_set_mem_table_withfd(fd_num, mr->name,
>                                                    reg->memory_size,
>                                                    reg->guest_phys_addr,
> @@ -455,7 +456,6 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
>              msg.payload.memory.regions[fd_num].guest_phys_addr =
>                  reg->guest_phys_addr;
>              msg.payload.memory.regions[fd_num].mmap_offset = offset;
> -            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
>              fds[fd_num++] = fd;
>          } else {
>              u->region_rb_offset[i] = 0;
> -- 
> 1.8.3.1