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List:       linux-driver-devel
Subject:    RE: [PATCH 1/2] PCI: hv: don't leak buffer in hv_pci_onchannelcallback()
From:       Jake Oshins <jakeo () microsoft ! com>
Date:       2016-05-31 17:27:20
Message-ID: DM2PR0301MB1232B9A84DFDBAED03D8AFFEAB460 () DM2PR0301MB1232 ! namprd03 ! prod ! outlook ! com
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> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Monday, May 30, 2016 7:18 AM
> To: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org; Bjorn
> Helgaas <bhelgaas@google.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Jake
> Oshins <jakeo@microsoft.com>
> Subject: [PATCH 1/2] PCI: hv: don't leak buffer in hv_pci_onchannelcallback()
> 
> We don't free buffer on several code paths in hv_pci_onchannelcallback(),
> put kfree() to the end of the function to fix the issue. Direct { kfree();
> return; } can now be replaced with a simple 'break';
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Jake Oshins <jakeo@microsoft.com>

> ---
>  drivers/pci/host/pci-hyperv.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 7e9b2de..a68ec49 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -1661,10 +1661,8 @@ static void hv_pci_onchannelcallback(void
> *context)
>  		 * All incoming packets must be at least as large as a
>  		 * response.
>  		 */
> -		if (bytes_recvd <= sizeof(struct pci_response)) {
> -			kfree(buffer);
> -			return;
> -		}
> +		if (bytes_recvd <= sizeof(struct pci_response))
> +			break;
>  		desc = (struct vmpacket_descriptor *)buffer;
> 
>  		switch (desc->type) {
> @@ -1679,8 +1677,7 @@ static void hv_pci_onchannelcallback(void
> *context)
>  			comp_packet->completion_func(comp_packet-
> >compl_ctxt,
>  						     response,
>  						     bytes_recvd);
> -			kfree(buffer);
> -			return;
> +			break;
> 
>  		case VM_PKT_DATA_INBAND:
> 
> @@ -1729,6 +1726,8 @@ static void hv_pci_onchannelcallback(void
> *context)
>  		}
>  		break;
>  	}
> +
> +	kfree(buffer);
>  }
> 
>  /**
> --
> 2.5.5

This is a good fix.  Thanks.

-- Jake Oshins

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