Commit 89140fda authored Feb 03, 2016 by Joe Lawrence Committed by Greg Kroah-Hartman Feb 04, 2016

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 d5ddcdf4 ("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>

parent 207b08b9

drivers/usb/host/xhci-ext-caps.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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;