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Commit 4307a28e authored by Andrea Righi's avatar Andrea Righi Committed by Greg Kroah-Hartman
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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: default avatarAndrea Righi <arighi@develer.com>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent e10fa478

drivers/usb/core/hcd.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -1218,6 +1218,11 @@ static int hcd_alloc_coherent(struct usb_bus *bus, 
{

{

	unsigned char *vaddr;

	unsigned char *vaddr;





	if (*vaddr_handle == NULL) {

		WARN_ON_ONCE(1);

		return -EFAULT;

	}



	vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr),

	vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr),

				 mem_flags, dma_handle);

				 mem_flags, dma_handle);

	if (!vaddr)

	if (!vaddr)

drivers/usb/host/ehci-hcd.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -629,6 +629,7 @@ static int ehci_init(struct usb_hcd *hcd) 
	ehci->command = temp;

	ehci->command = temp;





	/* Accept arbitrarily long scatter-gather lists */

	/* Accept arbitrarily long scatter-gather lists */

	if (!(hcd->driver->flags & HCD_LOCAL_MEM))

		hcd->self.sg_tablesize = ~0;

		hcd->self.sg_tablesize = ~0;

	return 0;

	return 0;

}

}