Re: [PATCH] block/nvme: Remove memory leak

[Stefano Garzarella]

On Tue, Apr 14, 2020 at 05:17:26PM +0200, Philippe Mathieu-Daudé wrote:
> Fixes: bdd6a90a9 ("Add VFIO based NVMe driver")
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  block/nvme.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/block/nvme.c b/block/nvme.c
> index 7b7c0cc5d6..9f3c7ab819 100644
> --- a/block/nvme.c
> +++ b/block/nvme.c
> @@ -163,6 +163,7 @@ static void nvme_init_queue(BlockDriverState *bs, 
> NVMeQueue *q,
>      }
>      r = qemu_vfio_dma_map(s->vfio, q->queue, bytes, false, &q->iova);
>      if (r) {
> +        qemu_vfree(q->queue);
>          error_setg(errp, "Cannot map queue");
>      }
>  }
> -- 
> 2.21.1
> 
> 

Are we adding a double free with this change?

IIUC when nvme_init_queue() fails in the nvme_create_queue_pair() we
already call the nvme_free_queue_pair() that frees sq.queue and
cq.queue.

I think your patch make the code cleaner, freeing the buffer near the
allocation during an error, maybe we can also set q->queue to NULL
after the qemu_vfree().

Thanks,
Stefano