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Date: Thu, 14 Aug 2014 12:37:18 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20140814103718.GJ31346@redhat.com>
References: <1408001361-13580-1-git-send-email-zhang.zhanghailiang@huawei.com>
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In-Reply-To: <1408001361-13580-4-git-send-email-zhang.zhanghailiang@huawei.com>
Subject: Re: [Qemu-devel] [PATCH v6 03/10] virtio-blk: fix reference a
 pointer which might be freed
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To: zhanghailiang <zhang.zhanghailiang@huawei.com>
Cc: kwolf@redhat.com, lkurusa@redhat.com, qemu-trivial@nongnu.org, jan.kiszka@siemens.com, riku.voipio@iki.fi, mjt@tls.msk.ru, qemu-devel@nongnu.org, lcapitulino@redhat.com, stefanha@redhat.com, luonengjun@huawei.com, pbonzini@redhat.com, peter.huangpeng@huawei.com, alex.bennee@linaro.org, rth@twiddle.net

On Thu, Aug 14, 2014 at 03:29:14PM +0800, zhanghailiang wrote:
> In function virtio_blk_handle_request, it may freed memory pointed by req,
> So do not access member of req after calling this function.
> 
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Stefan want to pick up this one?

> ---
>  hw/block/virtio-blk.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index c241c50..54a853a 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -458,7 +458,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>  static void virtio_blk_dma_restart_bh(void *opaque)
>  {
>      VirtIOBlock *s = opaque;
> -    VirtIOBlockReq *req = s->rq;
> +    VirtIOBlockReq *req = s->rq, *next = NULL;
>      MultiReqBuffer mrb = {
>          .num_writes = 0,
>      };
> @@ -469,8 +469,9 @@ static void virtio_blk_dma_restart_bh(void *opaque)
>      s->rq = NULL;
>  
>      while (req) {
> +        next = req->next;
>          virtio_blk_handle_request(req, &mrb);
> -        req = req->next;
> +        req = next;
>      }
>  
>      virtio_submit_multiwrite(s->bs, &mrb);
> -- 
> 1.7.12.4
>