From e955a1cd086de4d165ae0f4c7be7289d84b63bdc Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Tue, 14 Aug 2012 16:44:49 -0400 Subject: [PATCH] xhci: Make handover code more robust My test platform (Intel DX79SI) boots reliably under BIOS, but frequently crashes when booting via UEFI. I finally tracked this down to the xhci handoff code. It seems that reads from the device occasionally just return 0xff, resulting in xhci_find_next_cap_offset generating a value that's larger than the resource region. We then oops when attempting to read the value. Sanity checking that value lets us avoid the crash. I've no idea what's causing the underlying problem, and xhci still doesn't actually *work* even with this, but the machine at least boots which will probably make further debugging easier. This should be backported to kernels as old as 2.6.31, that contain the commit 66d4eadd8d067269ea8fead1a50fe87c2979a80d "USB: xhci: BIOS handoff and HW initialization." Signed-off-by: Matthew Garrett Signed-off-by: Sarah Sharp Cc: stable@vger.kernel.org --- drivers/usb/host/pci-quirks.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c index 20b9f45..966d148 100644 --- a/drivers/usb/host/pci-quirks.c +++ b/drivers/usb/host/pci-quirks.c @@ -841,12 +841,12 @@ static void __devinit quirk_usb_handoff_xhci(struct pci_dev *pdev) void __iomem *op_reg_base; u32 val; int timeout; + int len = pci_resource_len(pdev, 0); if (!mmio_resource_enabled(pdev, 0)) return; - base = ioremap_nocache(pci_resource_start(pdev, 0), - pci_resource_len(pdev, 0)); + base = ioremap_nocache(pci_resource_start(pdev, 0), len); if (base == NULL) return; @@ -856,9 +856,17 @@ static void __devinit quirk_usb_handoff_xhci(struct pci_dev *pdev) */ ext_cap_offset = xhci_find_next_cap_offset(base, XHCI_HCC_PARAMS_OFFSET); do { + if ((ext_cap_offset + sizeof(val)) > len) { + /* We're reading garbage from the controller */ + dev_warn(&pdev->dev, + "xHCI controller failing to respond"); + return; + } + if (!ext_cap_offset) /* We've reached the end of the extended capabilities */ goto hc_init; + val = readl(base + ext_cap_offset); if (XHCI_EXT_CAPS_ID(val) == XHCI_EXT_CAPS_LEGACY) break; -- 2.7.4