Commit 4307a28e authored Jun 28, 2010 by Andrea Righi Committed by Greg Kroah-Hartman Aug 10, 2010

USB: EHCI: fix NULL pointer dererence in HCDs that use HCD_LOCAL_MEM



If we use the HCD_LOCAL_MEM flag and dma_declare_coherent_memory() to
enforce the host controller's local memory utilization we also need to
disable native scatter-gather support, otherwise hcd_alloc_coherent() in
map_urb_for_dma() is called with urb->transfer_buffer == NULL, that
triggers a NULL pointer dereference.

We can also consider to add a WARN_ON() and return an error code to
better catch this problem in the future.

At the moment no driver seems to hit this bug, so I should
consider this a low-priority fix.

Signed-off-by: Andrea Righi <arighi@develer.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent e10fa478

drivers/usb/core/hcd.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -1218,6 +1218,11 @@ static int hcd_alloc_coherent(struct usb_bus *bus,
		{
		unsigned char *vaddr;

		if (*vaddr_handle == NULL) {
		WARN_ON_ONCE(1);
		return -EFAULT;
		}

		vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr),
		mem_flags, dma_handle);
		if (!vaddr)

drivers/usb/host/ehci-hcd.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -629,6 +629,7 @@ static int ehci_init(struct usb_hcd *hcd)
		ehci->command = temp;

		/* Accept arbitrarily long scatter-gather lists */
		if (!(hcd->driver->flags & HCD_LOCAL_MEM))
		hcd->self.sg_tablesize = ~0;
		return 0;
		}

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