lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 10 Jan 2020 15:43:28 +0000 From: Andre Przywara <andre.przywara@....com> To: Radhey Shyam Pandey <radheys@...inx.com> Cc: "David S . Miller" <davem@...emloft.net>, Michal Simek <michals@...inx.com>, Robert Hancock <hancock@...systems.ca>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 03/14] net: axienet: Fix DMA descriptor cleanup path On Fri, 10 Jan 2020 15:14:46 +0000 Radhey Shyam Pandey <radheys@...inx.com> wrote: Hi Radhey, thanks for having a look! > > -----Original Message----- > > From: Andre Przywara <andre.przywara@....com> > > Sent: Friday, January 10, 2020 5:24 PM > > To: David S . Miller <davem@...emloft.net>; Radhey Shyam Pandey > > <radheys@...inx.com> > > Cc: Michal Simek <michals@...inx.com>; Robert Hancock > > <hancock@...systems.ca>; netdev@...r.kernel.org; linux-arm- > > kernel@...ts.infradead.org; linux-kernel@...r.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@....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? Do you mean because .phys would be 0 if not initialised? AFAIK 0 can be a valid DMA address, so there is no special check for that, and unmapping DMA address 0 will probably go wrong at some point. So it's unlike kfree(NULL). Cheers, Andre. > > + 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 >
Powered by blists - more mailing lists