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

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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>
This commit is contained in:
Andrea Righi 2010-06-28 16:56:45 +02:00 committed by Greg Kroah-Hartman
parent e10fa4787f
commit 4307a28eb0
2 changed files with 7 additions and 1 deletions
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5
drivers/usb/core/hcd.c
View File

@ -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)

3
drivers/usb/host/ehci-hcd.c
View File

@ -629,7 +629,8 @@ static int ehci_init(struct usb_hcd *hcd)
ehci->command = temp;
/* Accept arbitrarily long scatter-gather lists */
hcd->self.sg_tablesize = ~0;
if (!(hcd->driver->flags & HCD_LOCAL_MEM))
hcd->self.sg_tablesize = ~0;
return 0;
}