From 3b9561e9d9b88eca9d4ed6aab025dec2eeeed501 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Tue, 7 May 2013 16:53:52 -0600 Subject: USB: set device dma_mask without reference to global data Many USB host drivers contain code such as: if (!pdev->dev.dma_mask) pdev->dev.dma_mask = &tegra_ehci_dma_mask; ... where tegra_ehci_dma_mask is a global. I suspect this code originated in commit 4a53f4e "USB: ehci-tegra: add probing through device tree" and was simply copied everywhere else. This works fine when the code is built-in, but can cause a crash when the code is in a module. The first module load sets up the dma_mask pointer, but if the module is removed and re-inserted, the value is now non-NULL, and hence is not updated to point at the new location, and hence points at a stale location within the previous module load address, which in turn causes a crash if the pointer is de-referenced. The simplest way of solving this seems to be to copy the code from ehci-platform.c, which uses the coherent_dma_mask as the target for the dma_mask pointer. Suggested-by: Arnd Bergmann Signed-off-by: Stephen Warren Acked-by: Tony Prisk Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-omap.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/usb/host/ehci-omap.c') diff --git a/drivers/usb/host/ehci-omap.c b/drivers/usb/host/ehci-omap.c index 3d1491b5f360..16d7150e8557 100644 --- a/drivers/usb/host/ehci-omap.c +++ b/drivers/usb/host/ehci-omap.c @@ -90,8 +90,6 @@ static const struct ehci_driver_overrides ehci_omap_overrides __initdata = { .extra_priv_size = sizeof(struct omap_hcd), }; -static u64 omap_ehci_dma_mask = DMA_BIT_MASK(32); - /** * ehci_hcd_omap_probe - initialize TI-based HCDs * @@ -146,8 +144,10 @@ static int ehci_hcd_omap_probe(struct platform_device *pdev) * Since shared usb code relies on it, set it here for now. * Once we have dma capability bindings this can go away. */ - if (!pdev->dev.dma_mask) - pdev->dev.dma_mask = &omap_ehci_dma_mask; + if (!dev->dma_mask) + dev->dma_mask = &dev->coherent_dma_mask; + if (!dev->coherent_dma_mask) + dev->coherent_dma_mask = DMA_BIT_MASK(32); hcd = usb_create_hcd(&ehci_omap_hc_driver, dev, dev_name(dev)); -- cgit v1.2.1