Messages in this thread | | | From | Radhey Shyam Pandey <> | Subject | RE: [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path | Date | Fri, 10 Jan 2020 15:14:46 +0000 |
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> -----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
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