Re: [PATCH v2] usb: xhci-pci: reorder removal to avoid use-after-free

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Hi,

On 14-08-19 16:32, 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 <carsten_schmid@xxxxxxxxxx>

Patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>

Regards,

Hans



---
v2:
   - more speaking name for private data element
   - consider failure in driver init sequence
   - fix minor issues found by checkpatch.pl
---
  drivers/usb/host/xhci-ext-caps.c | 25 +++++++++++++++----------
  drivers/usb/host/xhci-pci.c      |  8 +++++++-
  drivers/usb/host/xhci-pci.h      | 20 ++++++++++++++++++++
  drivers/usb/host/xhci.h          |  1 +
  4 files changed, 43 insertions(+), 11 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..28a7d53ecf2c 100644
--- a/drivers/usb/host/xhci-ext-caps.c
+++ b/drivers/usb/host/xhci-ext-caps.c
@@ -7,21 +7,19 @@
#include <linux/platform_device.h>
  #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->role_switch_pdev = pdev;
return 0;
  }
@@ -88,3 +82,14 @@ 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->role_switch_pdev) {
+		platform_device_unregister(priv->role_switch_pdev);
+		priv->role_switch_pdev = NULL;
+	}
+}
+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..f2201f380c17 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -14,6 +14,7 @@
  #include <linux/acpi.h>
#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,
  };
@@ -350,7 +352,7 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
  	retval = usb_add_hcd(xhci->shared_hcd, dev->irq,
  			IRQF_SHARED);
  	if (retval)
-		goto put_usb3_hcd;
+		goto remove_ext_cap;
  	/* Roothub already marked as USB 3.0 speed */
if (!(xhci->quirks & XHCI_BROKEN_STREAMS) &&
@@ -368,6 +370,8 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
return 0; +remove_ext_cap:
+	xhci_ext_cap_remove(xhci);
  put_usb3_hcd:
  	usb_put_hcd(xhci->shared_hcd);
  dealloc_usb2_hcd:
@@ -393,6 +397,8 @@ 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..fc0cde231679
--- /dev/null
+++ b/drivers/usb/host/xhci-pci.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * 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 *role_switch_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);




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