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authorJoe Lawrence <joe.lawrence@stratus.com>2016-02-03 12:51:12 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-04 17:00:10 -0800
commit89140fdaf11aec81e93d5590a993720f2ef0d26e (patch)
treec7abad88a88cfe4fe2d599eff868a59e18f16f17
parent207b08b9426dfaa63fcfea4156be0acb5b46ee38 (diff)
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>
-rw-r--r--drivers/usb/host/xhci-ext-caps.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 04ce6b156b35..e0244fb3903d 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;