From 89140fdaf11aec81e93d5590a993720f2ef0d26e Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@stratus.com>
Date: Wed, 3 Feb 2016 12:51:12 -0500
Subject: [PATCH] xhci: harden xhci_find_next_ext_cap against device removal
xhci_find_next_ext_cap doesn't check for PCI hotplug removal and may use
the PCI master abort bit pattern (~0) to calculate a new PCI address
offset to read/write. The has lead to reproducable crashes when testing
surprise removal during device initialization on a Stratus platform, at
least after commit d5ddcdf4d672 ("xhci: rework xhci extended capability
list parsing functions").
The crash is repeatable on a Stratus platform when injecting hardware
faults to induce xHCI host controller hotplug during driver
initialization. If a PCI read in xhci_find_next_ext_cap returns the
master abort pattern, quirk_usb_handoff_xhci may start using a bogus
ext_cap_offset to start searching more bogus PCI addresses.
Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/host/xhci-ext-caps.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 04ce6b156b350e..e0244fb3903dc8 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -112,12 +112,16 @@ static inline int xhci_find_next_ext_cap(void __iomem *base, u32 start, int id)
offset = start;
if (!start || start == XHCI_HCC_PARAMS_OFFSET) {
val = readl(base + XHCI_HCC_PARAMS_OFFSET);
+ if (val == ~0)
+ return 0;
offset = XHCI_HCC_EXT_CAPS(val) << 2;
if (!offset)
return 0;
};
do {
val = readl(base + offset);
+ if (val == ~0)
+ return 0;
if (XHCI_EXT_CAPS_ID(val) == id && offset != start)
return offset;
--
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