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[84.106.84.65]) by smtp.gmail.com with ESMTPSA id ng6sm10794969ejb.13.2019.08.14.05.54.31 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 14 Aug 2019 05:54:31 -0700 (PDT) Subject: Re: [PATCH] usb: xhci-pci: reorder removal to avoid use-after-free To: "Schmid, Carsten" Cc: "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" References: <1565782781938.37795@mentor.com> From: Hans de Goede Message-ID: <15aa45c7-6e45-d03f-9336-4291f8b2dc66@redhat.com> Date: Wed, 14 Aug 2019 14:54:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1565782781938.37795@mentor.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi, On 14-08-19 13:39, Schmid, Carsten wrote: > On driver removal, the platform_device_unregister call > attached through devm_add_action_or_reset was executed > after usb_hcd_pci_remove. > This lead to a use-after-free for the iomem resorce of > the xhci-ext-caps driver in the platform removal > because the parent of the resource was freed earlier. > > Fix this by reordering of the removal sequence. > > Signed-off-by: Carsten Schmid Assuming this has been tested, overal this looks good to me. But there are 2 things to fix: 1) Maybe pick a more descriptive struct member name then pdev. pdev with pci-devices often points to a pci_device ... How about: role_switch_pdev ? 2) xhci_ext_cap_init() is not the last call which can fail in xhci_pci_probe(), since you now no longer use devm_add_action_or_reset for auto-cleanup, you must now manually cleanup by calling xhci_ext_cap_remove() when later steps of xhci_pci_probe() fail. it looks like you will need a new ext_cap_remove error-exit label for this put above the put_usb3_hcd label and goto this new label instead of to put_usb3_hcd in all error paths after a successful call to xhci_ext_cap_init() Regards, Hans > --- > drivers/usb/host/xhci-ext-caps.c | 22 ++++++++++++---------- > drivers/usb/host/xhci-pci.c | 4 ++++ > drivers/usb/host/xhci-pci.h | 19 +++++++++++++++++++ > drivers/usb/host/xhci.h | 1 + > 4 files changed, 36 insertions(+), 10 deletions(-) > create mode 100644 drivers/usb/host/xhci-pci.h > > diff --git a/drivers/usb/host/xhci-ext-caps.c b/drivers/usb/host/xhci-ext-caps.c > index 399113f9fc5c..d2ab1e2a39c0 100644 > --- a/drivers/usb/host/xhci-ext-caps.c > +++ b/drivers/usb/host/xhci-ext-caps.c > @@ -7,21 +7,19 @@ > > #include > #include "xhci.h" > +#include "xhci-pci.h" > > #define USB_SW_DRV_NAME "intel_xhci_usb_sw" > #define USB_SW_RESOURCE_SIZE 0x400 > > -static void xhci_intel_unregister_pdev(void *arg) > -{ > - platform_device_unregister(arg); > -} > - > static int xhci_create_intel_xhci_sw_pdev(struct xhci_hcd *xhci, u32 cap_offset) > { > struct usb_hcd *hcd = xhci_to_hcd(xhci); > struct device *dev = hcd->self.controller; > struct platform_device *pdev; > struct resource res = { 0, }; > + struct xhci_pci_priv *priv = (struct xhci_pci_priv *)xhci->priv; > + > int ret; > > pdev = platform_device_alloc(USB_SW_DRV_NAME, PLATFORM_DEVID_NONE); > @@ -52,11 +50,7 @@ static int xhci_create_intel_xhci_sw_pdev(struct xhci_hcd *xhci, u32 cap_offset) > return ret; > } > > - ret = devm_add_action_or_reset(dev, xhci_intel_unregister_pdev, pdev); > - if (ret) { > - dev_err(dev, "couldn't add unregister action for intel_xhci_usb_sw pdev\n"); > - return ret; > - } > + priv->pdev = pdev; > > return 0; > } > @@ -88,3 +82,11 @@ int xhci_ext_cap_init(struct xhci_hcd *xhci) > return 0; > } > EXPORT_SYMBOL_GPL(xhci_ext_cap_init); > + > +void xhci_ext_cap_remove(struct xhci_hcd *xhci) > +{ > + struct xhci_pci_priv *priv = (struct xhci_pci_priv *)xhci->priv; > + if (priv->pdev) > + platform_device_unregister(priv->pdev); > +} > +EXPORT_SYMBOL_GPL(xhci_ext_cap_remove); > diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c > index c2fe218e051f..a4d094df56f7 100644 > --- a/drivers/usb/host/xhci-pci.c > +++ b/drivers/usb/host/xhci-pci.c > @@ -14,6 +14,7 @@ > #include > > #include "xhci.h" > +#include "xhci-pci.h" > #include "xhci-trace.h" > > #define SSIC_PORT_NUM 2 > @@ -62,6 +63,7 @@ static struct hc_driver __read_mostly xhci_pci_hc_driver; > static int xhci_pci_setup(struct usb_hcd *hcd); > > static const struct xhci_driver_overrides xhci_pci_overrides __initconst = { > + .extra_priv_size = sizeof(struct xhci_pci_priv), > .reset = xhci_pci_setup, > }; > > @@ -393,6 +395,8 @@ static void xhci_pci_remove(struct pci_dev *dev) > xhci->shared_hcd = NULL; > } > > + xhci_ext_cap_remove(xhci); > + > /* Workaround for spurious wakeups at shutdown with HSW */ > if (xhci->quirks & XHCI_SPURIOUS_WAKEUP) > pci_set_power_state(dev, PCI_D3hot); > diff --git a/drivers/usb/host/xhci-pci.h b/drivers/usb/host/xhci-pci.h > new file mode 100644 > index 000000000000..ead9618d7368 > --- /dev/null > +++ b/drivers/usb/host/xhci-pci.h > @@ -0,0 +1,19 @@ > +/* > + * xhci-pci.h - xHCI extended capability handling platform Glue. > + * > + * Copyright (C) 2019 Mentor Graphics (Deutschland) GmbH > + * Derived from xhci-plat.h > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License > + * version 2 as published by the Free Software Foundation. > + */ > + > +#ifndef _XHCI_PCI_H > +#define _XHCI_PCI_H > + > +struct xhci_pci_priv { > + struct platform_device *pdev; > +}; > + > +#endif /* _XHCI_PCI_H */ > diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h > index fabbce1c542a..847d2021fc2c 100644 > --- a/drivers/usb/host/xhci.h > +++ b/drivers/usb/host/xhci.h > @@ -2052,6 +2052,7 @@ void xhci_init_driver(struct hc_driver *drv, > const struct xhci_driver_overrides *over); > int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id); > int xhci_ext_cap_init(struct xhci_hcd *xhci); > +void xhci_ext_cap_remove(struct xhci_hcd *xhci); > > int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup); > int xhci_resume(struct xhci_hcd *xhci, bool hibernated); >