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Date:   Mon, 31 Jan 2022 17:10:25 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Christian Gmeiner <christian.gmeiner@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Tom Joseph <tjoseph@cadence.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        linux-omap@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] Revert "PCI: j721e: Drop redundant struct device *"
Message-ID: <20220131231025.GA516499@bhelgaas>
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On Mon, Jan 31, 2022 at 12:06:21PM +0100, Christian Gmeiner wrote:
> Am Do., 27. Jan. 2022 um 23:29 Uhr schrieb Bjorn Helgaas <helgaas@kernel.org>:
> >
> > On Mon, Jan 24, 2022 at 01:21:22PM +0100, Christian Gmeiner wrote:
> > > This reverts commit 19e863828acf6d8ac8475ba1fd93c0fe17fdc4ef.
> > >
> > > Fixes the following oops:
> > >  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
> >
> > Hi Christian,
> >
> > Would you mind trying this patch?
> >
> 
> Works - thanks. You can add my Tested-by.

Thanks, applied to for-linus for v5.17.

> 
> > commit 9d36a93af8fe ("PCI: j721e: Initialize pcie->cdns_pcie before using it")
> > Author: Bjorn Helgaas <bhelgaas@google.com>
> > Date:   Thu Jan 27 15:49:49 2022 -0600
> >
> >     PCI: j721e: Initialize pcie->cdns_pcie before using it
> >
> >     Christian reported a NULL pointer dereference in j721e_pcie_probe() caused
> >     by 19e863828acf ("PCI: j721e: Drop redundant struct device *"), which
> >     removed struct j721e_pcie.dev since there's another copy in struct
> >     cdns_pcie.dev reachable via j721e_pcie->cdns_pcie->dev.
> >
> >     The problem is that j721e_pcie->cdns_pcie was dereferenced before being
> >     initialized:
> >
> >       j721e_pcie_probe
> >         pcie = devm_kzalloc()             # struct j721e_pcie
> >         j721e_pcie_ctrl_init(pcie)
> >           dev = pcie->cdns_pcie->dev      <-- dereference cdns_pcie
> >         switch (mode) {
> >         case PCI_MODE_RC:
> >           cdns_pcie = ...                 # alloc as part of pci_host_bridge
> >           pcie->cdns_pcie = cdns_pcie     <-- initialize pcie->cdns_pcie
> >
> >     Initialize pcie->cdns_pcie before it is used.
> >
> >     Fixes: 19e863828acf ("PCI: j721e: Drop redundant struct device *")
> >     Reported-by: Christian Gmeiner <christian.gmeiner@gmail.com>
> >     Link: https://lore.kernel.org/r/20220124122132.435743-1-christian.gmeiner@gmail.com
> >     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> >
> > diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
> > index 489586a4cdc7..5d950c1d9fd0 100644
> > --- a/drivers/pci/controller/cadence/pci-j721e.c
> > +++ b/drivers/pci/controller/cadence/pci-j721e.c
> > @@ -372,10 +372,48 @@ static int j721e_pcie_probe(struct platform_device *pdev)
> >
> >         mode = (u32)data->mode;
> >
> > +       switch (mode) {
> > +       case PCI_MODE_RC:
> > +               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_HOST))
> > +                       return -ENODEV;
> > +
> > +               bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
> > +               if (!bridge)
> > +                       return -ENOMEM;
> > +
> > +               if (!data->byte_access_allowed)
> > +                       bridge->ops = &cdns_ti_pcie_host_ops;
> > +               rc = pci_host_bridge_priv(bridge);
> > +               rc->quirk_retrain_flag = data->quirk_retrain_flag;
> > +               rc->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
> > +
> > +               cdns_pcie = &rc->pcie;
> > +               break;
> > +       case PCI_MODE_EP:
> > +               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_EP))
> > +                       return -ENODEV;
> > +
> > +               ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
> > +               if (!ep)
> > +                       return -ENOMEM;
> > +
> > +               ep->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
> > +
> > +               cdns_pcie = &ep->pcie;
> > +               break;
> > +       default:
> > +               dev_err(dev, "INVALID device type %d\n", mode);
> > +               return 0;
> > +       }
> > +
> > +       cdns_pcie->dev = dev;
> > +       cdns_pcie->ops = &j721e_pcie_ops;
> > +
> >         pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> >         if (!pcie)
> >                 return -ENOMEM;
> >
> > +       pcie->cdns_pcie = cdns_pcie;
> >         pcie->mode = mode;
> >         pcie->linkdown_irq_regfield = data->linkdown_irq_regfield;
> >
> > @@ -426,28 +464,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
> >
> >         switch (mode) {
> >         case PCI_MODE_RC:
> > -               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_HOST)) {
> > -                       ret = -ENODEV;
> > -                       goto err_get_sync;
> > -               }
> > -
> > -               bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
> > -               if (!bridge) {
> > -                       ret = -ENOMEM;
> > -                       goto err_get_sync;
> > -               }
> > -
> > -               if (!data->byte_access_allowed)
> > -                       bridge->ops = &cdns_ti_pcie_host_ops;
> > -               rc = pci_host_bridge_priv(bridge);
> > -               rc->quirk_retrain_flag = data->quirk_retrain_flag;
> > -               rc->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
> > -
> > -               cdns_pcie = &rc->pcie;
> > -               cdns_pcie->dev = dev;
> > -               cdns_pcie->ops = &j721e_pcie_ops;
> > -               pcie->cdns_pcie = cdns_pcie;
> > -
> >                 gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> >                 if (IS_ERR(gpiod)) {
> >                         ret = PTR_ERR(gpiod);
> > @@ -497,23 +513,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
> >
> >                 break;
> >         case PCI_MODE_EP:
> > -               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_EP)) {
> > -                       ret = -ENODEV;
> > -                       goto err_get_sync;
> > -               }
> > -
> > -               ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
> > -               if (!ep) {
> > -                       ret = -ENOMEM;
> > -                       goto err_get_sync;
> > -               }
> > -               ep->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
> > -
> > -               cdns_pcie = &ep->pcie;
> > -               cdns_pcie->dev = dev;
> > -               cdns_pcie->ops = &j721e_pcie_ops;
> > -               pcie->cdns_pcie = cdns_pcie;
> > -
> >                 ret = cdns_pcie_init_phy(dev, cdns_pcie);
> >                 if (ret) {
> >                         dev_err(dev, "Failed to init phy\n");
> > @@ -525,8 +524,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
> >                         goto err_pcie_setup;
> >
> >                 break;
> > -       default:
> > -               dev_err(dev, "INVALID device type %d\n", mode);
> >         }
> >
> >         return 0;
> 
> 
> 
> -- 
> greets
> --
> Christian Gmeiner, MSc
> 
> https://christian-gmeiner.info/privacypolicy