From 89140fdaf11aec81e93d5590a993720f2ef0d26e Mon Sep 17 00:00:00 2001 From: Joe Lawrence 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 Acked-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman --- 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 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; -- 2.20.1