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Date: Sat, 28 Mar 2009 20:32:35 -0500
From: Anthony Liguori <aliguori@us.ibm.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH] check for bs->drv in bdrv_flush
References: <20090328183916.GA25875@lst.de>
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To: qemu-devel@nongnu.org

Christoph Hellwig wrote:
> All the bdrv_ helpers should check for bs->drv being zero as that means
> there is no backend image open.  bdrv_flush fails to perform that check
> and can thus cause NULL pointer dereferences.
>
> Found using qemu-io.
>   

Applied.  Thanks.

FWIW, I plan to include qemu-io once you rebase the series to use 
IOVectors instead of struct iovec.  It looks like a useful tool!

Regards,

Anthony Liguori

> Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c	2009-03-19 21:48:12.180978074 +0100
> +++ qemu/block.c	2009-03-19 21:48:53.228977807 +0100
> @@ -979,6 +979,8 @@ const char *bdrv_get_device_name(BlockDr
>  
>  void bdrv_flush(BlockDriverState *bs)
>  {
> +    if (!bs->drv)
> +        return;
>      if (bs->drv->bdrv_flush)
>          bs->drv->bdrv_flush(bs);
>      if (bs->backing_hd)
>
>
>
>
>