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From: Radhey Shyam Pandey <radheys@xilinx.com>
To: Andre Przywara <andre.przywara@arm.com>,
	"David S . Miller" <davem@davemloft.net>
Cc: Michal Simek <michals@xilinx.com>,
	Robert Hancock <hancock@sedsystems.ca>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path
Date: Fri, 10 Jan 2020 15:14:46 +0000
Message-ID: <CH2PR02MB7000F64AB27D352E00DC77A7C7380@CH2PR02MB7000.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20200110115415.75683-4-andre.przywara@arm.com>

> -----Original Message-----
> From: Andre Przywara <andre.przywara@arm.com>
> Sent: Friday, January 10, 2020 5:24 PM
> To: David S . Miller <davem@davemloft.net>; Radhey Shyam Pandey
> <radheys@xilinx.com>
> Cc: Michal Simek <michals@xilinx.com>; Robert Hancock
> <hancock@sedsystems.ca>; netdev@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path
> 
> When axienet_dma_bd_init() bails out during the initialisation process,
> it might do so with parts of the structure already allocated and
> initialised, while other parts have not been touched yet. Before
> returning in this case, we call axienet_dma_bd_release(), which does not
> take care of this corner case.
> This is most obvious by the first loop happily dereferencing
> lp->rx_bd_v, which we actually check to be non NULL *afterwards*.
> 
> Make sure we only unmap or free already allocated structures, by:
> - directly returning with -ENOMEM if nothing has been allocated at all
> - checking for lp->rx_bd_v to be non-NULL *before* using it
> - only unmapping allocated DMA RX regions
> 
> This avoids NULL pointer dereferences when initialisation fails.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  .../net/ethernet/xilinx/xilinx_axienet_main.c | 43 ++++++++++++-------
>  1 file changed, 28 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 97482cf093ce..7e90044cf2d9 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -160,24 +160,37 @@ static void axienet_dma_bd_release(struct
> net_device *ndev)
>  	int i;
>  	struct axienet_local *lp = netdev_priv(ndev);
> 
> +	/* If we end up here, tx_bd_v must have been DMA allocated. */
> +	dma_free_coherent(ndev->dev.parent,
> +			  sizeof(*lp->tx_bd_v) * lp->tx_bd_num,
> +			  lp->tx_bd_v,
> +			  lp->tx_bd_p);
> +
> +	if (!lp->rx_bd_v)
> +		return;
> +
>  	for (i = 0; i < lp->rx_bd_num; i++) {
> -		dma_unmap_single(ndev->dev.parent, lp->rx_bd_v[i].phys,
> -				 lp->max_frm_size, DMA_FROM_DEVICE);
> +		/* A NULL skb means this descriptor has not been initialised
> +		 * at all.
> +		 */
> +		if (!lp->rx_bd_v[i].skb)
> +			break;
> +
>  		dev_kfree_skb(lp->rx_bd_v[i].skb);
> -	}
> 
> -	if (lp->rx_bd_v) {
> -		dma_free_coherent(ndev->dev.parent,
> -				  sizeof(*lp->rx_bd_v) * lp->rx_bd_num,
> -				  lp->rx_bd_v,
> -				  lp->rx_bd_p);
> -	}
> -	if (lp->tx_bd_v) {
> -		dma_free_coherent(ndev->dev.parent,
> -				  sizeof(*lp->tx_bd_v) * lp->tx_bd_num,
> -				  lp->tx_bd_v,
> -				  lp->tx_bd_p);
> +		/* For each descriptor, we programmed cntrl with the (non-
> zero)
> +		 * descriptor size, after it had been successfully allocated.
> +		 * So a non-zero value in there means we need to unmap it.
> +		 */

> +		if (lp->rx_bd_v[i].cntrl)

I think it should ok to unmap w/o any check?
> +			dma_unmap_single(ndev->dev.parent, lp-
> >rx_bd_v[i].phys,
> +					 lp->max_frm_size,
> DMA_FROM_DEVICE);
>  	}
> +
> +	dma_free_coherent(ndev->dev.parent,
> +			  sizeof(*lp->rx_bd_v) * lp->rx_bd_num,
> +			  lp->rx_bd_v,
> +			  lp->rx_bd_p);
>  }
> 
>  /**
> @@ -207,7 +220,7 @@ static int axienet_dma_bd_init(struct net_device
> *ndev)
>  					 sizeof(*lp->tx_bd_v) * lp-
> >tx_bd_num,
>  					 &lp->tx_bd_p, GFP_KERNEL);
>  	if (!lp->tx_bd_v)
> -		goto out;
> +		return -ENOMEM;
> 
>  	lp->rx_bd_v = dma_alloc_coherent(ndev->dev.parent,
>  					 sizeof(*lp->rx_bd_v) * lp-
> >rx_bd_num,
> --
> 2.17.1


  reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 11:54 [PATCH 00/14] net: axienet: Error handling, SGMII and 64-bit DMA fixes Andre Przywara
2020-01-10 11:54 ` [PATCH 01/14] net: xilinx: temac: Relax Kconfig dependencies Andre Przywara
2020-01-10 14:19   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 02/14] net: axienet: Propagate failure of DMA descriptor setup Andre Przywara
2020-01-10 14:54   ` Radhey Shyam Pandey
2020-01-10 17:53     ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path Andre Przywara
2020-01-10 15:14   ` Radhey Shyam Pandey [this message]
2020-01-10 15:43     ` Andre Przywara
2020-01-10 17:05       ` Radhey Shyam Pandey
2020-01-16 18:03         ` Andre Przywara
2020-01-20 18:32           ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 04/14] net: axienet: Improve DMA error handling Andre Przywara
2020-01-10 15:26   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 05/14] net: axienet: Factor out TX descriptor chain cleanup Andre Przywara
2020-01-10 18:04   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 06/14] net: axienet: Check for DMA mapping errors Andre Przywara
2020-01-13  5:54   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 07/14] net: axienet: Fix SGMII support Andre Przywara
2020-01-10 14:04   ` Andrew Lunn
2020-01-10 14:20     ` Andre Przywara
2020-01-10 14:26       ` Andrew Lunn
2020-01-10 15:04       ` Russell King - ARM Linux admin
2020-01-10 15:22         ` Russell King - ARM Linux admin
2020-01-10 17:04           ` Russell King - ARM Linux admin
2020-01-18 11:22             ` Russell King - ARM Linux admin
2020-01-20 14:50               ` Andre Przywara
2020-01-20 15:45                 ` Russell King - ARM Linux admin
2020-01-27 17:04                   ` Andre Przywara
2020-01-27 17:20                     ` Radhey Shyam Pandey
2020-01-27 18:53                     ` Russell King - ARM Linux admin
2020-01-10 14:58   ` Russell King - ARM Linux admin
2020-01-10 17:32     ` Andre Przywara
2020-01-10 18:05       ` Russell King - ARM Linux admin
2020-01-10 19:33         ` Andrew Lunn
2020-01-10 11:54 ` [PATCH 08/14] net: axienet: Drop MDIO interrupt registers from ethtools dump Andre Przywara
2020-01-13  6:02   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 09/14] net: axienet: Add mii-tool support Andre Przywara
2020-01-13  6:12   ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 10/14] net: axienet: Wrap DMA pointer writes to prepare for 64 bit Andre Przywara
2020-01-10 11:54 ` [PATCH 11/14] net: axienet: Upgrade descriptors to hold 64-bit addresses Andre Przywara
2020-01-14 16:35   ` Radhey Shyam Pandey
2020-01-14 17:29     ` Andre Przywara
2020-01-10 11:54 ` [PATCH 12/14] net: axienet: Autodetect 64-bit DMA capability Andre Przywara
2020-01-10 14:08   ` Andrew Lunn
2020-01-10 14:13     ` Andre Przywara
2020-01-10 14:22       ` Andrew Lunn
2020-01-10 15:08         ` Andre Przywara
2020-01-10 15:22           ` Andrew Lunn
2020-01-14 17:03   ` Radhey Shyam Pandey
2020-01-14 17:41     ` Andre Przywara
2020-01-15  6:02       ` Radhey Shyam Pandey
2020-01-10 11:54 ` [PATCH 13/14] net: axienet: Allow DMA to beyond 4GB Andre Przywara
2020-01-10 11:54 ` [PATCH 14/14] net: axienet: Update devicetree binding documentation Andre Przywara
2020-01-21 21:51   ` Rob Herring
2020-01-24 16:29     ` Andre Przywara
2020-01-27  9:28       ` Radhey Shyam Pandey

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